Headlight module and headlight device

ABSTRACT

A headlight module includes a light source, a light guide element, and a projection optical element. The light source emits light. The light guide element has a reflecting surface for reflecting light emitted from the light source and an emitting surface for emitting light reflected by the reflecting surface. The projection optical element projects light emitted from the emitting surface. In a direction of an optical axis of the projection optical element, an end portion on the emitting surface side of the reflecting surface includes a point located at a focal position of the projection optical element.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of co-pending application Ser. No.15/907,772, filed on Feb. 28, 2018. Application Ser. No. 15/907,772 is aDivisional of co-pending U.S. application Ser. No. 15/037,533, filed onMay 18, 2016, (U.S. Pat. No. 9,945,528, issued on Apr. 17, 2018), whichis a US National Phase under 35 USC § 371 of International ApplicationNo. PCT/JP2014/080212, filed on Nov. 14, 2014, which claims benefitunder 35 U.S.C. § 119(a) to Application No. 2013-238884, filed in Japanon Nov. 19, 2013, all of which are hereby expressly incorporated byreference into the present application.

TECHNICAL FIELD

The present invention relates to a headlight module and a headlightdevice for irradiating an area in front of a vehicle or the like.

BACKGROUND ART

Headlight devices for vehicles need to have a predetermined lightdistribution pattern specified by road traffic rules or the like. “Lightdistribution” refers to a luminous intensity distribution of a lightsource with respect to space. That is, it refers to a spatialdistribution of light emitted from a light source. Further, “luminousintensity” indicates the degree of intensity of light emitted by aluminous body and is obtained by dividing the luminous flux passingthrough a small solid angle in a given direction by the small solidangle.

As one of the road traffic rules, for example, a predetermined lightdistribution pattern for an automobile low beam has a horizontally longshape narrow in an up-down direction. To prevent an oncoming vehiclefrom being dazzled, a boundary (cutoff line) of light on the upper sideof the light distribution pattern is required to be sharp. That is, asharp cutoff line with a dark area above the cutoff line (outside thelight distribution pattern) and a bright area below the cutoff line(inside the light distribution pattern) is required.

“Cutoff line” here refers to a light/dark borderline formed when a wallor screen is irradiated with light from a headlight, and a borderline onthe upper side of the light distribution pattern. That is, it refers toa light/dark borderline on the upper side of the light distributionpattern. It refers to a borderline on the upper side of the lightdistribution pattern and between a bright area (inside of the lightdistribution pattern) and a dark area (outside of the light distributionpattern). Cutoff line is a term used when an irradiating direction of aheadlight for passing each other is adjusted. The headlight for passingeach other is also referred to as a low beam.

The illuminance is required to be highest at a region on the lower sideof the cutoff line (inside the light distribution pattern). The regionof highest illuminance is referred to as the “high illuminance region.”Here, “region on the lower side of the cutoff line” refers to an upperpart of the light distribution pattern, and corresponds to a part forirradiating a distant area, in a headlight device. To achieve such asharp cutoff line, large chromatic aberration, blur, or the like mustnot occur on the cutoff line. “Blur occurs on the cutoff line” indicatesthat the cutoff line is unclear.

Further, as another example of the road traffic rules, foridentification of pedestrians and signs, it needs to have a “risingline” along which the irradiation on a walkway side rises. This is inorder to visually recognize people, signs, or the like on the walkwayside without dazzling oncoming vehicles. “Rising line along which theirradiation rises” here refers to the shape of the light distributionpattern of a low beam that is horizontal on an oncoming vehicle side andobliquely rises from the oncoming vehicle side toward a walkway side.

The “low beam” is a downward beam and used in passing an oncomingvehicle or the like. Typically, the low beam illuminates an area about40 m ahead. Further, “up-down direction” refers to a directionperpendicular to the ground surface (road surface). A vehicle headlightdevice needs to provide this complicated light distribution pattern.

To provide such a complicated light distribution pattern, aconfiguration using a light blocking plate or the like is commonly used.In this configuration, the light blocking plate or the like blockslight, thereby reducing use efficiency of light. Hereinafter, useefficiency of light will be referred to as “light use efficiency.”

Patent Reference 1 discloses a technique that forms a cutoff line byusing a light blocking plate.

PRIOR ART REFERENCES Patent References

Patent Reference 1: Japanese Patent Application Publication No.2009-199938

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

However, since the configuration of Patent Reference 1 forms the cutoffline using the light blocking plate, the light use efficiency is low.Specifically, part of light emitted from a light source is blocked bythe light blocking plate and is not used as projection light.

The present invention is made in view of the problems of the prior art,and is intended to provide a headlight device that reduces reduction ofthe light use efficiency.

Means for Solving the Problems

A headlight module includes: a light source for emitting light; a lightguide element having a reflecting surface for reflecting the light andan emitting surface for emitting light reflected by the reflectingsurface; and a projection optical element for projecting light emittedfrom the emitting surface, wherein in a direction of an optical axis ofthe projection optical element, an end portion on the emitting surfaceside of the reflecting surface includes a point located at a focalposition of the projection optical element.

Effect of the Invention

According to the present invention, it is possible to provide aheadlight module or a headlight device that reduces reduction of thelight use efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1(A) and 1(B) are configuration diagrams illustrating aconfiguration of a headlight module 100 according to a first embodiment.

FIG. 2 is a perspective view of a light guide component 3 of theheadlight module 100 according to the first embodiment.

FIG. 3 is an explanatory diagram for explaining a light concentrationposition PH of the headlight module 100 according to the firstembodiment.

FIG. 4 is an explanatory diagram for explaining a light concentrationposition PH of the headlight module 100 according to the firstembodiment.

FIG. 5 is a configuration diagram illustrating a configuration of theheadlight module 100 according to the first embodiment.

FIG. 6 is a diagram illustrating, in contour display, an illuminancedistribution of the headlight module 100 according to the firstembodiment.

FIG. 7 is a diagram illustrating, in contour display, an illuminancedistribution of the headlight module 100 according to the firstembodiment.

FIG. 8 is a perspective view of a light guide component 30 of theheadlight module 100 according to the first embodiment.

FIG. 9 is a schematic diagram illustrating an example of a shape of anemitting surface 32 of the light guide component 3 of the headlightmodule 100 according to the first embodiment.

FIG. 10 is a configuration diagram illustrating a configuration of theheadlight module 100 according to a first modification example of thefirst embodiment.

FIGS. 11(A) and 11(B) are diagrams illustrating shapes of a condensinglens 2 of the headlight module 100 according to a second modificationexample of the first embodiment.

FIG. 12 is a configuration diagram illustrating a configuration of theheadlight module 100 according to the second modification example of thefirst embodiment.

FIGS. 13(A) and 13(B) are diagrams illustrating shapes of light guidecomponents 3 and 35 of the headlight module 100 according to a thirdmodification example of the first embodiment.

FIG. 14 is a configuration diagram illustrating a configuration of aheadlight module 110 according to a fourth modification example of thefirst embodiment.

FIG. 15 is a configuration diagram illustrating a configuration of aheadlight module 120 according to a second embodiment.

FIGS. 16(A) and 16(B) are schematic diagrams illustrating lightdistribution patterns 103 and 104 of a motorcycle.

FIG. 17 is an explanatory diagram illustrating a tilt angle d of avehicle body.

FIGS. 18(A) and 18(B) are schematic diagrams illustrating lightdistribution patterns corrected by the headlight module 120 according tothe second embodiment.

FIG. 19 is a configuration diagram illustrating a configuration of aheadlight module 130 according to a third embodiment.

FIGS. 20(A) and 20(B) are diagrams each illustrating an irradiated areawhen a vehicle with the headlight module 130 according to the thirdembodiment is cornering.

FIG. 21 is a configuration diagram illustrating a configuration of aheadlight module 140 according to the third embodiment.

FIG. 22 is a configuration diagram illustrating a configuration of aheadlight module 150 according to a fourth embodiment.

FIG. 23 is a configuration diagram illustrating a configuration of aheadlight device 250 with headlight modules according to a fifthembodiment of the present invention.

MODES FOR CARRYING OUT THE INVENTION

Recently, from the viewpoint of reducing the burden on the environment,such as reducing emission of carbon dioxide (CO₂) and consumption offuel, it is desired to improve energy efficiency of vehicles, forexample. Accordingly, in vehicle headlight devices, downsizing, weightreduction, and improvement of power efficiency are required. Thus, it isdesired to employ, as a light source of a vehicle headlight device, asemiconductor light source having high luminous efficiency as comparedto conventional halogen bulbs (lamp light sources).

“Semiconductor light source” refers to, for example, a light emittingdiode (LED), laser diode (LD), or the like. “Vehicle headlight device”refers to an illuminating device that is mounted on a transportationmachine or the like and used to improve visibility for an operator andconspicuity to the outside. A vehicle headlight device is also referredto as a headlamp or headlight.

A conventional lamp light source (bulb light source) is a light sourcehaving directivity lower than that of a semiconductor light source.Thus, a lamp light source uses a reflecting mirror (reflector) to givedirectivity to the emitted light. On the other hand, a semiconductorlight source has at least one light emitting surface and emits light tothe light emitting surface side. In this manner, a semiconductor lightsource is different from a lamp light source in light emittingcharacteristics, and therefore requires an optical system suitable forthe semiconductor light source instead of a conventional optical systemusing a reflecting mirror.

From the above-described characteristics of a semiconductor lightsource, for example, a light source of the present invention, describedlater, may include an organic electroluminescence (organic EL) lightsource that is a type of solid-state light sources. Also, for example, asolid-state light source, described later, may include a light sourcethat irradiates phosphor applied on a plane with excitation light tocause the phosphor to emit light.

Excluding bulb light sources, light sources having directivity arereferred to as “solid-state light sources.” “Directivity” refers to aproperty that the intensity of light or the like emitted into spacevaries depending on direction. “Having directivity” here indicates thatlight travels to the light emitting surface side and does not travel tothe side opposite to the light emitting surface, as described above.That is, it indicates that the divergence angle of light emitted fromthe light source is 180 degrees or less. Thus, a reflecting mirror suchas a reflector is not particularly necessary.

The above-described Patent Reference 1 discloses a technique in which asemiconductor light source is disposed at a first focal point of areflector with an ellipsoid of revolution, light emitted from thesemiconductor light source is concentrated at a second focal point, andparallel light is emitted by a projection lens. Patent Reference 1 alsodiscloses a technique for headlights using semiconductor light sources.That is, Patent Reference 1 discloses a technique that uses asemiconductor light source and gives directivity by using a reflector.

Further, to achieve a complicated light distribution pattern, such as asharp cutoff line or rising line as described above, a configurationusing a polyhedral reflector, a light blocking plate, or the like iscommonly used. This enlarges and complicates the optical system. Theconfiguration of Patent Reference 1 also uses a reflector, and thereforehas a large optical system.

Further, in general, downsizing of an optical system reduces the lightuse efficiency. Thus, it is necessary to achieve a small-sized opticalsystem having high light use efficiency. Further, as described above,the use of a light blocking plate reduces the light use efficiency.“Light use efficiency” refers to use efficiency of light.

Embodiments described below use a solid-state light source and givedirectivity without using a reflector. Thus, the embodiments describedbelow can provide a small headlight device that uses a solid-state lightsource and reduces reduction of the light use efficiency.

Examples of the embodiments of the present invention will be describedbelow with reference to the drawings by taking vehicle headlights asexamples. In the following description of the embodiments, to facilitateexplanation, xyz-coordinates will be used. It will be assumed that aleft-right direction of a vehicle is the x axis direction; the rightdirection with respect to a forward direction of the vehicle is the +xaxis direction; the left direction with respect to the forward directionof the vehicle is the −x axis direction. Here, “forward direction”refers to a traveling direction of the vehicle. That is, “forwarddirection” refers to a direction in which the headlight radiates light.It will be assumed that an up-down direction of the vehicle is the yaxis direction; the upward direction is the +y axis direction; thedownward direction is the −y axis direction. The “upward direction” is adirection toward the sky; the “downward direction” is a direction towardthe ground (road surface or the like). It will be assumed that thetraveling direction of the vehicle is the z axis direction; thetraveling direction is the +z axis direction; the opposite direction isthe −z axis direction. The +z axis direction will be referred to as the“forward direction”; the −z axis direction will be referred to as the“backward direction”. That is, the +z axis direction is the direction inwhich the headlight radiates light.

As described above, in the following embodiments, a z-x plane is a planeparallel to a road surface. This is because the road surface is usuallyconsidered to be a “horizontal plane.” Thus, a z-x plane is consideredas a “horizontal plane.” “Horizontal plane” refers to a planeperpendicular to the direction of gravity. However, the road surface maybe inclined with respect to the traveling direction of the vehicle.Specifically, it is an uphill, a downhill, or the like. In these cases,the “horizontal plane” is considered as a plane parallel to the roadsurface. That is, the “horizontal plane” is not a plane perpendicular tothe direction of gravity.

On the other hand, a typical road surface is seldom inclined in theleft-right direction with respect to the traveling direction of thevehicle. “Left-right direction” refers to a width direction of a road.In these cases, the “horizontal plane” is considered as a planeperpendicular to the direction of gravity. For example, even if a roadsurface is inclined in the left-right direction and the vehicle isupright with respect to the left-right direction of the road surface,this is considered to be equivalent to a state in which the vehicle istilted with respect to the “horizontal plane” in the left-rightdirection.

To simplify explanation, the following description will be made on theassumption that the “horizontal plane” is a plane perpendicular to thedirection of gravity. That is, the description will be made on theassumption that a z-x plane is a plane perpendicular to the direction ofgravity.

Further, the light sources described in the following embodiments areillustrated as light sources having directivity. Typical examplesinclude semiconductor light sources, such as light emitting diodes orlaser diodes. The light sources also include organic electroluminescencelight sources, light sources that irradiate phosphor applied on planeswith excitation light to cause the phosphor to emit light, or the like.Light sources having directivity other than bulb light sources arereferred to as “solid-state light sources.”

The light sources described in the embodiments do not include bulb lightsources, such as incandescent lamps, halogen lamps, or fluorescentlamps, that have no directivity and require reflectors or the like. Thisis because the use of a bulb light source makes it difficult to meet thedemand for improvement in energy efficiency or the demand for downsizingof the device, as described above. However, with respect to the demandfor improving the light use efficiency without using a light blockingplate, the light sources may be bulb light sources, such as incandescentlamps, halogen lamps, or fluorescent lamps.

The present invention is applicable to a low beam, a high beam, or thelike of a vehicle headlight device. The present invention is alsoapplicable to a low beam, a high beam, or the like of a motorcycleheadlight. The present invention is also applicable to headlights forother vehicles, such as three-wheelers or four-wheelers.

However, in the following description, a case where a light distributionpattern of a low beam of a motorcycle headlight is formed will bedescribed as an example. The light distribution pattern of the low beamof the motorcycle headlight has a cutoff line that is a straight lineparallel to the left-right direction (x axis direction) of the vehicle.Further, it is brightest at a region on the lower side of the cutoffline (inside the light distribution pattern).

“Light distribution pattern” refers to a shape of a light beam and anintensity distribution of light due to the direction of light emittedfrom a light source. “Light distribution pattern” will also be used tomean an illuminance pattern on an irradiated surface 9 described below.Further, “light distribution” refers to a distribution of intensity oflight emitted from a light source with respect to the direction of thelight. “Light distribution” will also be used to mean an illuminancedistribution on the irradiated surface 9 described below.

Further, the four-wheeler is, for example, a normal four-wheeledautomobile or the like. Further, the three-wheeler is, for example, amotor tricycle called a gyro. “Motor tricycle called a gyro” refers to ascooter with three wheels including one front wheel and two rear wheelsabout one axis. In Japan, it corresponds to a motorbike. It has arotational axis near the center of the vehicle body and allows most ofthe vehicle body including the front wheel and a driver seat to betilted in the left-right direction. This mechanism allows the center ofgravity to move inward during turning, similarly to a motorcycle.

First Embodiment

FIGS. 1(A) and 1(B) are configuration diagrams illustrating aconfiguration of a headlight module 100 according to a first embodiment.FIG. 1(A) is a diagram as viewed from the right (+x axis direction) withrespect to the forward direction of the vehicle. FIG. 1(B) is a diagramas viewed from the top (+y axis direction).

As illustrated in FIG. 1, the headlight module 100 according to thefirst embodiment includes a light source 1, a light guide component 3,and a projection lens 4. The headlight module 100 according to the firstembodiment may include a condensing lens 2. In the headlight module 100,the condensing optical element 2 may be mounted to the light source 1 toform a unit.

<Light Source 1>

The light source 1 has a light emitting surface 11. The light source 1emits light for illuminating an area in front of the vehicle from thelight emitting surface 11. The light source 1 is located on the −z axisside of the condensing lens 2. As the light source 1, a light emittingdiode, a laser diode, an electroluminescence element, or the like may beused. However, the following description assumes that the light source 1is a light emitting diode (LED).

<Condensing Lens 2>

The condensing lens 2 is located on the +z axis side of the light source1. The condensing lens 2 is also located on the −z axis side of thelight guide component 3.

The condensing lens 2 is a lens having positive power. That is, thecondensing lens 2 is an optical element having positive power. The poweris also referred to as “refractive power.”

The condensing lens 2 is an example of an optical element having acondensing function. That is, the condensing lens 2 is an example of acondensing optical element having a condensing function.

The condensing lens 2 includes, for example, incident surfaces 211 and212, a reflecting surface 22, and emitting surfaces 231 and 232.

In each of the following embodiments, as an example, the condensing lens2 will be described as a condensing optical element having the followingfunctions. Specifically, the condensing lens 2 concentrates, due torefraction, light rays emitted from the light source 1 at small emissionangles. The condensing lens 2 also concentrates, due to reflection,light rays emitted from the light source 1 at large emission angles.

The condensing lens 2 receives light emitted from the light source 1.The condensing lens 2 concentrates light at an arbitrary position in theforward direction (+z axis direction). The light concentration positionof the condensing lens 2 will be described with reference to FIGS. 3 and4.

In FIG. 1, the condensing lens 2 is formed by a single optical lens, butmay use multiple optical lenses. However, use of multiple optical lensesreduces manufacturability due to reasons, such as ensuring the accuracyof positioning of each optical lens. That is, it makes manufacturingdifficult.

The condensing lens 2 is disposed immediately after the light source 1.“After” here refers to a side toward which light emitted from the lightsource 1 travels. The following embodiments assume that the travelingdirection of the light is the +z axis direction. Here, “immediatelyafter” indicates that light emitted from the light emitting surface 11is directly incident on the condensing lens 2.

A light emitting diode emits light with a Lambertian light distribution.“Lambertian light distribution” refers to a light distribution in whichthe luminance of a light emitting surface is constant regardless of theviewing direction. That is, the divergence angle of light distributionof a light emitting diode is wide. Thus, by reducing the distancebetween the light source 1 and the condensing lens 2, it is possible toincrease the amount of light incident on the condensing lens 2.

The condensing lens 2 is made of, for example, transparent resin, glass,or silicone. The material of the condensing lens 2 may be any materialhaving transparency, and may be transparent resin or the like. However,from the viewpoint of light use efficiency, materials having hightransparency are appropriate as the material of the condensing lens 2.Further, since the condensing lens 2 is disposed immediately after thelight source 1, the material of the condensing lens 2 preferably hasexcellent heat resistance.

The incident surface 211 is an incident surface formed at a central partof the condensing lens 2. Specifically, an optical axis of thecondensing lens 2 has an intersection on the incident surface 211.

The incident surface 211 has a convex shape having positive power. Theconvex shape of the incident surface 211 is a shape projecting in the −zaxis direction. The power is also referred to as the “refractive power.”The incident surface 211 has, for example, a shape rotationallysymmetric about the optical axis of the condensing lens 2.

The incident surface 212 has, for example, a shape that is a part of thesurface shape of a solid of revolution obtained by rotating an ellipseabout its major or minor axis. A solid of revolution obtained byrotating an ellipse about its major or minor axis is referred to as a“spheroid.” A rotational axis of the spheroid coincides with the opticalaxis of the condensing lens 2. The incident surface 212 has a surfaceshape obtained by cutting off both ends of the spheroid in the directionof the rotational axis. Thus, the incident surface 212 has a tubularshape.

One end (end on the +z axis direction side) of the tubular shape of theincident surface 212 is connected to the outer periphery of the incidentsurface 211. The tubular shape of the incident surface 212 is formed onthe −z axis direction side of the incident surface 211. That is, thetubular shape of the incident surface 212 is formed on the light source1 side of the incident surface 211.

The reflecting surface 22 has a tubular shape whose cross-sectionalshape in an x-y plane is, for example, a circular shape centered on theoptical axis of the condensing lens 2. In the tubular shape of thereflecting surface 22, the diameter of the circular shape in the x-yplane at the end on the −z axis direction side is smaller than thediameter of the circular shape in the x-y plane at the end on the +zaxis direction side. Specifically, the diameter of the reflectingsurface 22 increases in the +z axis direction. For example, thereflecting surface 22 has the shape of the side surface of a circulartruncated cone. However, the shape of the reflecting surface 22 in aplane including the optical axis of the condensing lens 2 may be acurved line shape. “Plane including the optical axis” indicates that theline of the optical axis can be drawn on the plane.

One end (end on the −z axis direction side) of the tubular shape of thereflecting surface 22 is connected to the other end (end on the −z axisdirection side) of the tubular shape of the incident surface 212.Specifically, the reflecting surface 22 is located on the outerperipheral side of the incident surface 212.

The emitting surface 231 is located on the +z axis direction side of theincident surface 211. Specifically, the optical axis of the condensinglens 2 has an intersection on the emitting surface 231.

The emitting surface 231 has a convex shape having positive power. Theconvex shape of the emitting surface 231 is a shape projecting in the +zaxis direction. The emitting surface 231 has, for example, a shaperotationally symmetric about the optical axis of the condensing lens 2.

The emitting surface 232 is located on the outer peripheral side of theemitting surface 231. The emitting surface 232 has, for example, aplanar shape parallel to an x-y plane. An inner periphery and an outerperiphery of the emitting surface 232 have circular shapes.

The inner periphery of the emitting surface 232 is connected to an outerperiphery of the emitting surface 231. The outer periphery of theemitting surface 232 is connected to the other end (end on the +z axisdirection side) of the tubular shape of the reflecting surface 22.

Of the light emitted from the light emitting surface 11, light rayshaving small emission angles are incident on the incident surface 211.The light rays having small emission angles have, for example, adivergence angle of 60 degrees or less. The light rays having smallemission angles are incident on the incident surface 211 and emittedfrom the emitting surface 231. The light rays with small emission anglesemitted from the emitting surface 231 are concentrated at an arbitraryposition in front (+z axis direction) of the condensing lens 2. Asdescribed above, the light concentration position will be describedlater.

Of the light emitted from the light emitting surface 11, light rayshaving large emission angles are incident on the incident surface 212.The light rays having large emission angles have, for example, adivergence angle greater than 60 degrees. The light rays incident on theincident surface 212 are reflected by the reflecting surface 22. Thelight rays reflected by the reflecting surface 22 travel in the +z axisdirection. The light rays reflected by the reflecting surface 22 areemitted from the emitting surface 232. The light rays with largeemission angles emitted from the emitting surface 232 are concentratedat an arbitrary position in front (+z axis direction) of the condensinglens 2. As described above, the light concentration position will bedescribed later.

In each of the following embodiments, as an example, the condensing lens2 will be described as an optical element having the followingfunctions: the condensing lens 2 concentrates, due to refraction, lightrays emitted from the light source 1 at small emission angles; thecondensing lens 2 also concentrates, due to reflection, light raysemitted from the light source 1 at large emission angles.

The light concentration position of the light rays emitted from theemitting surface 232 and the light concentration position of the lightrays emitted from the emitting surface 231 need not coincide. Forexample, the light concentration position of the light emitted from theemitting surface 232 may be closer to the condensing lens 2 than thelight concentration position of the light emitted from the emittingsurface 231.

For example, the light concentration position of the light emitted fromthe emitting surface 231 has a shape similar to a pattern of the lightsource 1 (shape of the light emitting surface 11). Thus, projection ofthe shape of the light emitting surface 11 of the light source 1 causeslight distribution unevenness. In such a case, by differentiating thelight concentration position of the light emitted from the emittingsurface 232 from the light concentration position of the light emittedfrom the emitting surface 231 as described above, it becomes possible toreduce the light distribution unevenness due to the light emitted fromthe emitting surface 231.

Further, in the first embodiment, each of the incident surfaces 211 and212, reflecting surface 22, and emitting surfaces 231 and 232 of thecondensing lens 2 has a shape rotationally symmetric about the opticalaxis. However, the shapes are not limited to rotationally symmetricshapes as long as it can concentrate light emitted from the light source1.

In particular, if the shape of the light emitting surface 11 of thelight source 1 is a rectangular shape, the condensing lens 2 can bedownsized by changing the cross-sectional shape of the reflectingsurface 22 in an x-y plane to an elliptical shape, for example.

Further, for example, by changing the cross-sectional shape of thereflecting surface 22 in an x-y plane to an elliptical shape, it ispossible to form a light concentration spot at the light concentrationposition into an elliptical shape. This facilitates formation of a widelight distribution pattern by the headlight module 100.

Further, the condensing lens 2 is only required to totally have positivepower. Each of the incident surfaces 211 and 212, reflecting surface 22,and emitting surfaces 231 and 232 may have any power.

As described above, if a bulb light source is employed as the lightsource 1, a reflecting mirror may be used as the condensing opticalelement.

<Light Guide Component 3>

The light guide component 3 is located on the +z axis side of thecondensing lens 2. The light guide component 3 is located on the −z axisside of the projection lens 4.

The light guide component 3 receives light emitted from the condensinglens 2. The light guide component 3 emits the light in the forwarddirection (+z axis direction). The light guide component 3 has afunction as a light guide element that guides light entering through anincident surface 31 to an emitting surface 32. That is, the light guidecomponent 3 is an example of a light guide element that guides lightentering through the incident surface 31 to the emitting surface 32.

The light guide component 3 is made of, for example, transparent resin,glass, silicone, or the like.

FIG. 2 is a perspective view of the light guide component 3. The lightguide component 3 has, for example, a column body shape with rectangularbases. “Column body” refers to a tubular spatial figure having two planefigures as bases. Surfaces of the column body other than the bases arereferred to as side surfaces. Further, the distance between the twobases of the column body is referred to as a height. The light incidentsurface 31 of the light guide component 3 corresponds to one of thebases. Further, the light emitting surface 32 of the light guidecomponent 3 corresponds to the other of the bases.

In FIG. 2, the incident surface 31 is a surface located on the −z axisside of the light guide component 3. The incident surface 31 faces anx-y plane. The emitting surface 32 is a surface located on the +z axisside of the light guide component 3. The emitting surface 32 faces anx-y plane. A reflecting surface 33 is a surface located on the −y axisside of the light guide component 3. The reflecting surface 33 faces az-x plane.

Bases of a column body are typically planes, but the incident surface 31of the light guide component 3 has a curved surface shape. Specifically,the light guide component 3 has a shape obtained by connecting a curvedsurface shape to a base of a column body.

In this first embodiment, a case where the shape of the incident surface31 of the light guide component 3 is a convex shape having positivepower will be described first.

If the light guide component 3 is considered as the above-describedcolumn body, the incident surface 31 corresponds to the base on the −zaxis side.

The shape of the incident surface 31 is a convex shape projecting in the−z axis direction. The shape of the incident surface 31 is formed by,for example, a part of a spherical surface. In the first embodiment, asection obtained by cutting the spherical surface by a plane passingthrough the spherical center is flush with the reflecting surface 33.Thus, the center of the spherical shape of the incident surface 31 is onthe same plane as the reflecting surface 33.

However, a plane parallel to the section obtained by cutting thespherical surface by a plane passing through the spherical center may beflush with the reflecting surface 33.

In FIG. 2, the incident surface 31 has a spherical portion and a planarportion. The planar portion of the incident surface 31 is located on theperiphery of the spherical portion.

If light is incident on the spherical portion of the incident surface31, the divergence angle of the light changes. By changing thedivergence angle of the light, it is possible to form the shape of thelight distribution pattern. That is, the incident surface 31 has afunction of forming the shape of the light distribution pattern. Thatis, the incident surface 31 functions as a light distribution patternshape forming portion.

Further, for example, by providing the incident surface 31 with a lightcondensing function, the condensing lens 2 can be omitted. That is, theincident surface 31 functions as a light condensing portion.

The incident surface 31 can be considered as an example of a lightdistribution pattern shape forming portion. The incident surface 31 canbe considered as an example of a light condensing portion.

If the light guide component 3 is considered as the above-describedcolumn body, the emitting surface 32 corresponds to the base on the +zaxis side.

In the first embodiment, the emitting surface 32 is indicated by aplane. The surface shape of the emitting surface 32 is not limited toplanar.

The emitting surface 32 is located at a position optically conjugate tothe irradiated surface 9, described later. Thus, a shape (image) oflight on the emitting surface 32 is projected onto the irradiatedsurface 9.

If the light guide component 3 has a tubular shape and its inner side isformed by a reflecting surface, the emitting surface 32 is an imaginarysurface.

The image of light on the emitting surface 32 is formed on a part of theemitting surface 32. Specifically, a light distribution pattern can beformed within the emitting surface 32 into a shape appropriate for theheadlight module 100. In particular, if a single light distributionpattern is formed by using multiple headlight modules, as describedlater, light distribution patterns corresponding to the roles of therespective headlight modules are formed. The maximum image of light onthe emitting surface 32 has the shape of the emitting surface 32.

If the light guide component 3 is considered as the above-describedcolumn body, the reflecting surface 33 corresponds to a side surface onthe −y axis side.

The reflecting surface 33 reflects light reaching the reflecting surface33. That is, the reflecting surface 33 has a function of reflectinglight. That is, the reflecting surface 33 functions as a lightreflecting portion.

The reflecting surface 33 is disposed at an end portion on the −y axisdirection side of the incident surface 31. In the first embodiment, anend portion on the −z axis direction side of the reflecting surface 33is connected to the end portion on the −y axis direction side of theincident surface 31.

The reflecting surface 33 is a surface facing in the +y axis direction.Specifically, a front surface of the reflecting surface 33 is a surfacefacing in the +y axis direction. A back surface of the reflectingsurface 33 is a surface facing in the −y axis direction. The frontsurface of the reflecting surface 33 is a surface for reflecting light.

The reflecting surface 33 need not be planar. That is, the surface shapeof the reflecting surface 33 is not limited to planar. The reflectingsurface 33 may have a curved surface shape. However, in the firstembodiment, the reflecting surface 33 is a plane. That is, in the firstembodiment, the reflecting surface 33 has a planar shape.

The reflecting surface 33 may be a mirror surface obtained by mirrordeposition. However, the reflecting surface 33 desirably functions as atotal reflection surface, without mirror deposition. This is because atotal reflection surface is higher in reflectance than a mirror surface,contributing improvement in light use efficiency. Further, eliminationof the step of mirror deposition can simplify the manufacturing processof the light guide component 3, contributing reduction in themanufacturing cost of the light guide component 3. In particular, theconfiguration illustrated in the first embodiment has a feature that theincident angles of light rays on the reflecting surface 33 are shallow,thus allowing the reflecting surface 33 to be used as a total reflectionsurface, without mirror deposition. “Incident angles are shallow”indicates that the incident angles are great.

An edge 321 is an edge on the −y axis side of the emitting surface 32.The edge 321 is an end portion on the −y axis side of the emittingsurface 32.

The edge 321 is an edge on the +z axis side of the reflecting surface33. The edge 321 is an end portion on the +z axis side of the reflectingsurface 33.

The edge 321 is a ridge line where the emitting surface 32 and thereflecting surface 33 intersect. That is, the edge 321 is a portion(ridge line portion) joining the emitting surface 32 and the reflectingsurface 33. “Ridge” refers to a line segment where two plane faces of apolyhedron intersect. Although the line segment typically refers to astraight line, it here also includes a curved line, a bent line, and thelike.

The edge 321 may have a straight line shape, a curved line shape, a bentline shape, and the like. “Bent line” refers to a bent line, e.g., anedge 321 having a “rising line” shape illustrated in FIG. 9 anddescribed later, and the like. In an example of the first embodiment,the edge 321 has a straight line shape parallel to the x axis.

Further, for example, if the light guide component 3 is hollow and theemitting surface 32 is an opening portion, the edge 321 is an endportion of the reflecting surface 33. That is, the edge 321 may includea boundary portion between two surfaces. The edge 321 may also includean end portion of a surface. The above-described edge 321 will also bereferred to below as the edge portion 321.

The edge 321 forms the shape of a cutoff line 91 of the lightdistribution pattern. This is because the emitting surface 32 is locatedat a position optically conjugate to the irradiated surface 9 and thusthe light distribution pattern on the irradiated surface 9 has a shapesimilar to that of the light distribution pattern on the emittingsurface 32. “Optically conjugate” refers to a relation in which lightemitted from one point is imaged at another point. Thus, the edge 321 ofthe emitting surface 32 is preferably formed into the shape of thecutoff line 91.

The irradiated surface 9 is a virtual surface defined at a predeterminedposition in front of the vehicle. The irradiated surface 9 is a surfaceparallel to an x-y plane. The predetermined position in front of thevehicle is a position at which the luminous intensity or illuminance ofthe headlight device is measured, and is specified in road traffic rulesor the like. For example, in Europe, United Nations Economic Commissionfor Europe (UNECE) specifies a position 25 m from a light source as theposition at which the luminous intensity of an automobile headlightdevice is measured. In Japan, Japanese Industrial Standards Committee(JIS) specifies a position 10 m from a light source as the position atwhich the luminous intensity is measured.

Further, “cutoff line” refers to a light/dark borderline formed on theupper side of the light distribution pattern when a wall or screen isirradiated with light from a headlight. “Cutoff line” refers to aborderline between a bright section and a dark section on the upper sideof the light distribution pattern. That is, the “cutoff line” is a partof a borderline between a bright section and a dark section formed onthe outline portion of the light distribution pattern. That is, the areaabove the cutoff line (outside the light distribution pattern) is darkand the area below the cutoff line (inside the light distributionpattern) is bright.

Cutoff line is a term used in adjustment of the emitting direction of aheadlight for passing each other. The headlight for passing each otheris also referred to as a low beam. The “cutoff line” is required to besharp. Here, “sharp” indicates that large chromatic aberration, blur, orthe like must not occur on the cutoff line.

<Projection Lens 4>

The projection lens 4 is located on the +z axis side of the light guidecomponent 3.

The projection lens 4 is a lens having positive power. An image of thelight distribution pattern formed on the emitting surface 32 ismagnified and projected by the projection lens 4 onto the irradiatedsurface 9 in front of the vehicle.

The projection lens 4 is a “projection optical element” for magnifyingand projecting an image of the light distribution pattern formed on theemitting surface 32. In the embodiments, as an example, the projectionoptical element will be described as the projection lens 4.

The projection lens 4 may consist of a single lens. The projection lens4 may also consist of multiple lenses. However, the light use efficiencydecreases as the number of lenses increases. Thus, the projection lens 4desirably consists of one or two lenses.

The projection lens 4 is made of transparent resin or the like. Further,the material of the projection lens 4 is not limited to transparentresin, and is only required to be a refractive material havingtransparency.

Further, the projection lens 4 is desirably disposed so that its opticalaxis is located on the lower side (−y axis side) of the optical axis ofthe light guide component 3.

The optical axis of the projection lens 4 is a line connecting centersof curvature of both surfaces of the lens. The optical axis of theprojection lens 4 is a normal passing through a surface apex of theprojection lens 4. In the case of FIG. 1, the optical axis of theprojection lens 4 is an axis passing through the surface apexes of theprojection lens 4 and being parallel to the z axis.

When the surface apexes of the projection lens 4 move parallel to the xaxis direction or y axis direction in x-y planes, the optical axis ofthe projection lens 4 also moves parallel to the x axis direction or yaxis direction similarly. Further, when the projection lens 4 tilts withrespect to an x-y plane, the normal at the surface apexes of theprojection lens 4 also tilts with respect to the x-y plane and thus theoptical axis of the projection lens 4 also tilts with respect to the x-yplane.

The optical axis of the light guide component 3 is a central axis of thelight guide component 3.

In FIG. 1, for example, the optical axis of the light guide component 3coincides with an optical axis of the light source 1 and the opticalaxis of the condensing lens 2. Further, the optical axis of the lightsource 1 coincides with a normal at a center position of the lightemitting surface 11.

Further, the projection lens 4 is disposed so that the position of theedge 321 of the emitting surface 32 of the light guide component 3 inthe y axis direction coincides with the position of the optical axis ofthe projection lens 4 in the y axis direction. Specifically, in FIG. 1,the edge 321 intersects with the optical axis of the projection lens 4.In FIG. 1, the edge 321 intersects with the optical axis of theprojection lens 4 at a right angle.

If the edge 321 is not linear, the plane passing through a position(point Q) at which the edge 321 intersects with the optical axis of theprojection lens 4 and being parallel to an x-y plane is in opticallyconjugate relation with the irradiated surface 9, for example. The edge321 need not necessarily intersect with the optical axis of theprojection lens 4.

Such an arrangement makes it possible to make the position of the cutoffline 91 on the irradiated surface 9 in the y axis direction coincidewith the position of a center of the light source 1 in the y axisdirection, without tilting the entire headlight module 100.

Of course, if the headlight module 100 is mounted at a tilt on thevehicle, the position at which the projection lens 4 is disposed may bechanged depending on the tilt. However, compared to adjustment of theentire headlight module 100, adjustment of the position of theprojection lens 4 adjusts a small component and thus can be easilyperformed.

<Behavior of Light Rays>

As illustrated in FIG. 1, the light concentrated by the condensing lens2 enters the light guide component 3 through the incident surface 31.

The incident surface 31 is a refractive surface. The light incident onthe incident surface 31 is refracted at the incident surface 31. Theincident surface 31 has a convex shape projecting in the −z axisdirection.

The curvature of the incident surface 31 in the x axis directioncontributes a “width of a light distribution” in a direction parallel toa road surface. Further, the curvature of the incident surface 31 in they axis direction contributes a “height of the light distribution” in adirection perpendicular to the road surface.

<Behavior of Light Rays on z-x Plane>

When viewed in a z-x plane, the incident surface 31 has a convex shapeand has positive power with respect to a horizontal direction (x axisdirection). Here, “when viewed in a z-x plane” refers to being viewedfrom the y axis direction. That is, it refers to being projected onto az-x plane and viewed. The light incident on the incident surface 31propagates in the light guide component 3 in such a manner as to befurther concentrated. Here, “propagate” refers to traveling of light inthe light guide component 3.

When viewed in a z-x plane, the light propagating in the light guidecomponent 3 is concentrated at an arbitrary light concentration positionPH in the light guide component 3 by the condensing lens 2 and theincident surface 31 of the light guide component 3, as illustrated inFIG. 1(B). The light concentration position PH is indicated by adot-and-dash line in FIG. 1(B). Thus, the light after passing throughthe light concentration position PH diverges. Thus, the emitting surface32 emits light wider in the horizontal direction than that at the lightconcentration position PH.

The emitting surface 32 is located at a position conjugate to theirradiated surface 9. Thus, the width of the light on the emittingsurface 32 in the horizontal direction corresponds to the “width of thelight distribution” on the irradiated surface 9. Thus, by changing thecurvature of the curved surface shape of the incident surface 31, it ispossible to arbitrarily change a width of the light distribution patternof light emitted by the headlight module 100.

Further, the light concentration position PH need not necessarily belocated in the light guide component 3. FIGS. 3 and 4 are explanatorydiagrams for explaining the light concentration position PH of theheadlight module 100 according to the first embodiment.

In FIG. 3, the light concentration position PH is located in front (onthe −z axis direction side) of the incident surface 31. That is, thelight concentration position PH is located in a gap between thecondensing lens 2 and the light guide component 3. “Gap” refers to aspace.

In the configuration of FIG. 3, as in the configuration of FIG. 1, lightafter passing through the light concentration position PH diverges. Thedivergence angle of the diverged light decreases at the incident surface31. However, since the distance from the light concentration position PHto the emitting surface 32 can be made large, the width of the lightbeam on the emitting surface 32 in the x axis direction can becontrolled. Thus, the emitting surface 32 emits light wide in thehorizontal direction (x axis direction).

In FIG. 4, the light concentration position PH is located in back (onthe +z axis direction side) of the emitting surface 32. Specifically,the light concentration position PH is located in a gap between thelight guide component 3 and the projection lens 4.

The light after passing through the emitting surface 32 concentrates atthe light concentration position PH. By controlling the distance fromthe emitting surface 32 to the light concentration position PH, it ispossible to control the width of the light beam on the emitting surface32 in the x axis direction. Thus, the emitting surface 32 emits lightwide in the horizontal direction (x axis direction).

FIG. 5 is a configuration diagram illustrating a configuration of theheadlight module 100 according to the first embodiment. As illustratedin FIG. 5, the headlight module 100 has no light concentration positionPH.

In the headlight module 100 illustrated in FIG. 5, a curved surface ofthe incident surface 31 in the horizontal direction (x axis direction)is a concave surface having negative power, for example. This can spreadlight in the horizontal direction at the emitting surface 32, providinga light distribution pattern wide in the horizontal direction at theirradiated surface 9.

Thus, the width of the light beam on the emitting surface 32 is largerthan the width of the light beam on the incident surface 31. Theincident surface 31 with the concave surface can control the width ofthe light beam on the emitting surface 32 in the x axis direction,providing a light distribution pattern wide in the horizontal directionat the irradiated surface 9.

The light concentration position PH indicates that light density perunit area on an x-y plane is high. Thus, if the light concentrationposition PH coincides in position with the emitting surface 32, thewidth of the light distribution on the irradiated surface 9 is minimum,and the illuminance of the light distribution on the irradiated surface9 is maximum.

Further, as the light concentration position PH separates from theemitting surface 32, the width of the light distribution on theirradiated surface 9 increases, and the illuminance of the lightdistribution on the irradiated surface 9 decreases. “Illuminance” refersto a physical quantity indicating brightness of light radiated to aplanar object. It is equal to a luminous flux radiated per unit area.

<Behavior of Light Rays on z-y Plane>

On the other hand, when the light incident on the incident surface 31 isviewed in a y-z plane, the light refracted at the incident surface 31propagates in the light guide component 3 and is guided to thereflecting surface 33. Here, “propagate” refers to traveling of light inthe light guide component 3.

Light entering the light guide component 3 and reaching the reflectingsurface 33 enters the light guide component 3 and directly reaches thereflecting surface 33. “Directly reach” refers to reaching without beingreflected by another surface or the like. Light entering the light guidecomponent 3 and reaching the reflecting surface 33 reaches thereflecting surface 33 without being reflected by another surface or thelike. That is, light reaching the reflecting surface 33 undergoes thefirst reflection in the light guide component 3.

Further, the light reflected by the reflecting surface 33 is directlyemitted from the emitting surface 32. That is, the light reflected bythe reflecting surface 33 reaches the emitting surface 32 without beingreflected by another surface or the like. That is, the light undergoingthe first reflection at the reflecting surface 33 reaches the emittingsurface 32 without undergoing further reflection.

In FIG. 1, light emitted from the part of the emitting surfaces 231 and232 on the +y axis direction side of the optical axis of the condensinglens 2 is guided to the reflecting surface 33. Further, light emittedfrom the part of the emitting surfaces 231 and 232 on the −y axisdirection side of the optical axis of the condensing lens 2 is emittedfrom the emitting surface 32 without being reflected by the reflectingsurface 33. That is, in FIG. 1, part of the light entering the lightguide component 3 reaches the reflecting surface 33. The light reachingthe reflecting surface 33 is reflected by the reflecting surface 33 andemitted from the emitting surface 32.

All of the light entering the light guide component 3 may reach thereflecting surface 33. As described later, by tilting the light source 1and condensing lens 2 with respect to the light guide component 3, it ispossible to cause all of the light emitted from the condensing lens 2 tobe reflected by the reflecting surface 33. Also, as described later, bytilting the reflecting surface 33 with respect to the optical axis ofthe projection lens 4, it is possible to cause all of the light emittedfrom the condensing lens 2 to be reflected by the reflecting surface 33.The light reaching the reflecting surface 33 is reflected by thereflecting surface 33 and then emitted from the emitting surface 32.

For a typical light guide component, light travels inside the lightguide component while being repeatedly reflected at a side surface ofthe light guide component. Thereby, the intensity distribution of thelight is equalized. In the present application, light entering the lightguide component 3 is reflected at the reflecting surface 33 only onceand emitted from the emitting surface 32. In this respect, the way ofusing the light guide component 3 in the present application differsfrom the conventional way of using a light guide component.

In a light distribution pattern specified in road traffic rules or thelike, a region on the lower side of the cutoff line 91 has the highestilluminance, for example. The emitting surface 32 of the light guidecomponent 3 and the irradiated surface 9 are in conjugate relation witheach other. Thus, to make a region on the lower side (−y axis directionside) of the cutoff line 91 on the irradiated surface 9 have the highestilluminance, it is required to make a region on the inner side (+y axisdirection side) of the edge 321 on the emitting surface 32 of the lightguide component 3 have the highest luminous intensity. “Luminousintensity” refers to a physical quantity indicating how strong lightemitted from a light source is.

If the edge 321 is not linear, the plane passing through a position atwhich the edge 321 intersects with the optical axis of the projectionlens 4 and being parallel to an x-y plane is in conjugate relation withthe irradiated surface 9, for example.

To produce such a light distribution pattern, it is effective that, whenviewed in a y-z plane, part of the light entering through the incidentsurface 31 of the light guide component 3 is reflected by the reflectingsurface 33, as illustrated in FIG. 1(A).

This is because light entering through the incident surface 31 andreaching the emitting surface 32 without being reflected at thereflecting surface 33 and light entering through the incident surface 31and reflected at the reflecting surface 33 are superposed on theemitting surface 32. Specifically, the light reaching the emittingsurface 32 without being reflected at the reflecting surface 33 and thelight reaching the emitting surface 32 after being reflected at thereflecting surface 33 are superposed in a region on the emitting surface32 corresponding to the high illuminance region on the irradiatedsurface 9. Such a configuration makes it possible to make a region onthe inner side (+y axis direction side) of the edge 321 on the emittingsurface 32 have the highest luminous intensity in the emitting surface32.

A region having high luminous intensity is formed by superposing, on theemitting surface 32, the light reaching the emitting surface 32 withoutbeing reflected at the reflecting surface 33 and the light reaching theemitting surface 32 after being reflected at the reflecting surface 33.

The position of the region having high luminous intensity on theemitting surface 32 can be changed by changing the reflection positionof the light on the reflecting surface 33. By setting the reflectionposition of the light on the reflecting surface 33 near the emittingsurface 32, it is possible to set the region having high luminousintensity near the edge 321 on the emitting surface 32. Thus, it ispossible to set a region having high illuminance on the lower side ofthe cutoff line 91 on the irradiated surface 9.

Further, the amount of the superposed light can be adjusted byarbitrarily changing the curvature of the incident surface 31 in avertical direction (y axis direction), as in the case of adjusting thewidth of the light distribution in the horizontal direction. “Amount ofthe superposed light” refers to the amount of light resulting from thesuperposition of the light reaching the emitting surface 32 withoutbeing reflected at the reflecting surface 33 and the light reflected atthe reflecting surface 33.

In this manner, by adjusting the curvature of the incident surface 31 inthe horizontal direction, a desired light distribution can be obtained.Here, “desired light distribution” refers to, for example, a lightdistribution specified in road traffic rules or the like. If a singlelight distribution pattern is formed by using multiple headlightmodules, as described later, “desired light distribution” refers to alight distribution required for each headlight module. That is, byadjusting the curvature of the incident surface 31 in the horizontaldirection, the light distribution can be adjusted.

Further, by adjusting the geometric relationship between the condensinglens 2 and the light guide component 3, a desired light distribution canbe obtained. Here, “desired light distribution” refers to, for example,a light distribution specified in road traffic rules or the like. If asingle light distribution pattern is formed by using multiple headlightmodules, as described later, “desired light distribution” refers to alight distribution required for each headlight module. That is, byadjusting the geometric relationship between the condensing lens 2 andthe light guide component 3, the light distribution can be adjusted.

“Geometric relationship” refers to, for example, the positionalrelationship between the condensing lens 2 and the light guide component3 in the optical axis direction. As the distance from the condensinglens 2 to the light guide component 3 decreases, the amount of lightreflected at the reflecting surface 33 decreases, and the dimension ofthe light distribution in the vertical direction (Y axis direction)decreases. That is, the height of the light distribution patterndecreases. Conversely, as the distance from the condensing lens 2 to thelight guide component 3 increases, the amount of light reflected at thereflecting surface 33 increases, and the dimension of the lightdistribution in the vertical direction (Y axis direction) increases.That is, the height of the light distribution pattern increases.

Further, the position of the superposed light can be changed byadjusting the position of the light reflected by the reflecting surface33. “Position of the superposed light” refers to the position at whichthe light reaching a region on the +Y axis direction side of the edge321 (on the emitting surface 32) without being reflected at thereflecting surface 33 and the light reflected at the reflecting surface33 are superposed on the emitting surface 32. That is, it refers to ahigh luminous intensity region on the emitting surface 32. The highluminous intensity region is a region on the emitting surface 32corresponding to the high illuminance region on the irradiated surface9.

Further, by adjusting a light concentration position of the lightreflected at the reflecting surface 33, the height of the high luminousintensity region on the emitting surface 32 can be adjusted.Specifically, if the light concentration position is near the emittingsurface 32, the dimension of the high luminous intensity region in theheight direction is small. Conversely, if the light concentrationposition is far from the emitting surface 32, the dimension of the highluminous intensity region in the height direction is large.

In the above description, the high illuminance region is described as aregion on the lower side (−Y axis direction side) of the cutoff line 91.This is the position of the high illuminance region in the lightdistribution pattern on the irradiated surface 9.

As described later, for example, a single light distribution pattern maybe formed on the irradiated surface 9 by using multiple headlightmodules. In such a case, the high luminous intensity region on theemitting surface 32 of each headlight module is not necessarily a regionon the +Y axis direction side of the edge 321. For each headlightmodule, the high luminous intensity region is formed, on the emittingsurface 32, at a position appropriate for the light distribution patternof the headlight module.

As described above, by adjusting the light concentration position PH inthe horizontal direction, a width of the light distribution pattern canbe controlled. Further, by adjusting a light concentration position inthe vertical direction, the height of the high illuminance region can becontrolled. As such, the light concentration position PH in thehorizontal direction and the light concentration position in thevertical direction need not necessarily coincide. By independentlysetting the light concentration position PH in the horizontal directionand the light concentration position in the vertical direction, it ispossible to control the shape of the light distribution pattern or theshape of the high illuminance region.

The cutoff line 91 can be easily formed by giving the shape of thecutoff line 91 to the edge 321 of the light guide component 3. That is,the shape of the cutoff line 91 can be easily formed by changing theshape of the edge 321 of the light guide component 3. Thus, there is anadvantage that the light use efficiency is high as compared to aconventional case where it is formed by using a light blocking plate.This is because the cutoff line 91 can be formed without blocking light.

An image of the light distribution pattern formed on the emittingsurface 32 is magnified and projected by the light guide component 3onto the irradiated surface 9 in front of the vehicle.

A focal position of the projection lens 4 coincides with a position ofthe edge 321 on the optical axis of the projection lens 4 (position inthe z axis direction). Specifically, a focal position of the projectionlens 4 is located at an intersection between the edge 321 and theoptical axis of the projection lens 4.

In another aspect, the position of a focal point of the projection lens4 in the z axis direction (optical axis direction of the projection lens4) coincides with a position of the edge 321 in the z axis direction.

<Light Distribution Pattern>

In the light distribution pattern of the low beam of the motorcycleheadlight device, the cutoff line 91 has a linear shape parallel to theleft-right direction (x axis direction) of the vehicle. That is, thecutoff line 91 has a linear shape extending in the left-right direction(X axis direction) of the vehicle.

Further, it is necessary that the light distribution pattern of the lowbeam of the motorcycle headlight device is brightest in a region on thelower side of the cutoff line 91. That is, a region on the lower side ofthe cutoff line 91 is a high illuminance region.

The emitting surface 32 of the light guide component 3 and theirradiated surface 9 are in optically conjugate relation with eachother. Thus, the edge 321 of the emitting surface 32 corresponds to thecutoff line 91 of the irradiated surface 9.

The headlight module 100 according to the first embodiment directlyprojects the light distribution pattern formed on the emitting surface32 onto the irradiated surface 9. Thus, the light distribution on theemitting surface 32 is projected onto the irradiated surface 9 as it is.Hence, to achieve a light distribution pattern that is brightest in aregion on the lower side of the cutoff line 91, it is necessary to form,on the emitting surface 32, a luminous intensity distribution in whichthe luminous intensity is highest near the edge 321.

FIGS. 6 and 7 are diagrams illustrating, in contour display, illuminancedistributions on the irradiated surface 9 of the headlight module 100according to the first embodiment. FIG. 6 is an illuminance distributionwhen the light guide component 3 illustrated in FIG. 2 is used. FIG. 7is an illuminance distribution when a light guide component 30illustrated in FIG. 8 is used. This illuminance distribution is anilluminance distribution projected on the irradiated surface 9 located25 m ahead (+z axis direction). Further, this illuminance distributionis obtained by simulation. “Contour display” refers to displaying bymeans of a contour plot. “Contour plot” refers to a diagram depicting aline joining points of equal value.

As illustrated in FIG. 2, the curved surface shape of the incidentsurface 31 of the light guide component 3 is a convex shape havingpositive power in both the horizontal and vertical directions.

As can be seen from FIG. 6, the cutoff line 91 of the light distributionpattern is a sharp straight line. That is, intervals between contourlines are small on the lower side of the cutoff line 91. The lightdistribution has a region having the highest illuminance (highilluminance region) 93 near the cutoff line 91.

In FIG. 6, a center of the high illuminance region 93 is located on the+y axis direction side of a center of the light distribution pattern. InFIG. 6, the entire high illuminance region 93 is on the +y axisdirection side of the center of the light distribution pattern. Thecenter of the light distribution pattern is a center of the lightdistribution pattern in its width direction and is a center of the lightdistribution pattern in its height direction.

It can be seen that a region 92 on the lower side of the cutoff line 91in the light distribution pattern is brightest. That is, the region 92on the lower side of the cutoff line 91 in the light distributionpattern includes the brightest region 93 in the light distributionpattern.

FIG. 8 is a perspective view of the light guide component 30 of theheadlight module 100 according to the first embodiment. FIG. 7 is adiagram illustrating, in contour display, an illuminance distribution onthe irradiated surface 9 obtained by using the light guide component 30illustrated in FIG. 8.

The incident surface 31 of the light guide component 30 illustrated inFIG. 8 has a concave shape having negative power in the horizontaldirection (x axis direction). Also, the incident surface 31 has a convexshape having positive power in the vertical direction (y axisdirection).

FIG. 7 illustrates, in contour display, an illuminance distributionprojected on the irradiated surface 9 located 25 m ahead (+z axisdirection) when the light guide component 30 is used. Further, thisilluminance distribution is obtained by simulation. The incident surface31 has negative power in the horizontal direction.

Thus, in the light distribution pattern illustrated in FIG. 7, the width(in the x axis direction) of the light distribution is wide, as comparedto the light distribution pattern illustrated in FIG. 6.

Further, in the light distribution pattern illustrated in FIG. 7, thecutoff line 91 is a sharp straight line. That is, intervals betweencontour lines are small on the lower side of the cutoff line 91. Thelight distribution has a region having the highest illuminance (highilluminance region) 93 near the cutoff line 91.

In FIG. 7, a center of the high illuminance region 93 is located on the+y axis direction side of a center of the light distribution pattern. InFIG. 7, the entire high illuminance region 93 is on the +y axisdirection side of the center of the light distribution pattern. Thecenter of the light distribution pattern is a center of the lightdistribution pattern in its width direction and is a center of the lightdistribution pattern in its height direction.

In the light distribution pattern illustrated in FIG. 7, a region 92 onthe lower side of the cutoff line 91 is illuminated most brightly. Thatis, the region 92 on the lower side of the cutoff line 91 in the lightdistribution pattern includes the brightest region 93 in the lightdistribution pattern.

In FIGS. 6 and 7, the region 92 on the lower side of the cutoff line 91is located between the center of the light distribution pattern and thecutoff line 91.

As above, by changing the curved surface shape of the incident surface31 of the light guide component 3, it is possible to easily form adesired light distribution pattern. Here, “desired light distributionpattern” refers to, for example, a light distribution pattern specifiedin road traffic rules or the like. In another aspect, if a single lightdistribution pattern is formed by using multiple headlight modules, asdescribed later, “desired light distribution pattern” refers to a lightdistribution pattern required for each headlight module.

As above, by changing the curved surface shape of the incident surface31 of the light guide component 3, it is possible to easily form a lightdistribution pattern. In particular, it is possible to make the region92 on the lower side of the cutoff line 91 brightest while keeping thesharp cutoff line 91.

Thus, to form the cutoff line 91, the headlight module 100 need not usea light blocking plate, which causes reduction in the light useefficiency, as in the conventional headlight device. Further, to providethe high illuminance region in the light distribution pattern, theheadlight module 100 needs no complicated optical system. Thus, theheadlight module 100 can provide a small and simple headlight devicehaving high light use efficiency.

The headlight module 100 according to the first embodiment of thepresent invention is described by taking a low beam of a motorcycleheadlight device as an example. However, the present invention is notlimited to this. For example, it is also applicable to a low beam of anautomobile headlight device or the like. Specifically, the headlightmodule 100 is also applicable to a low beam of a headlight device for amotor tricycle or a low beam of a headlight device for a four-wheeledautomobile.

FIG. 9 is a schematic diagram illustrating an example of the shape ofthe emitting surface 32 of the light guide component 3. The shape of theedge 321 of the emitting surface 32 may be, for example, a stepped shapeas illustrated in FIG. 9. That is, the shape of the edge 321 illustratedin FIG. 9 is a bent line shape described above. When viewed from therear side (−z axis direction), in the shape of the edge 321, an edge 321_(a) on the left side (−x axis direction side) is located above (+y axisdirection) an edge 321 _(b) on the right side (+x axis direction side).

The emitting surface 32 and the irradiated surface 9 are in opticallyconjugate relation with each other. Thus, the shape of the lightdistribution pattern on the emitting surface 32 is projected on theirradiated surface 9. Thus, on the irradiated surface 9, a cutoff lineon the left side in the traveling direction of the vehicle is high and acutoff line on the right side is low. This makes it possible to easilyform a “rising line” along which the irradiation on a walkway side risesfor identification of pedestrians and signs. The description is made bytaking, as an example, a vehicle traveling in the left lane of a road.

Further, in some vehicles, multiple headlight modules are arranged, andthe light distribution patterns of the respective modules are combinedto form a desired light distribution pattern. That is, a lightdistribution pattern may be formed by arranging multiple headlightmodules and combining the light distribution patterns of the respectivemodules. Here, “desired light distribution pattern” refers to, forexample, a light distribution pattern specified in road traffic rules orthe like. Even in such a case, the headlight module 100 according to thefirst embodiment can be easily applied.

In the headlight module 100, by adjusting the curved surface shape ofthe incident surface 31 of the light guide component 3, it is possibleto arbitrarily change the width and height of light distribution of thelight distribution pattern. It is then possible to arbitrarily changethe light distribution.

Further, in the headlight module 100, by adjusting the opticalpositional relationship between the condensing lens 2 and the lightguide component 3, it is possible to arbitrarily change the width andheight of light distribution of the light distribution pattern. It isthen possible to arbitrarily change the light distribution.

Further, by using the reflecting surface 33, it is possible to easilychange the light distribution. For example, as described later, bychanging an inclination angle e of the reflecting surface 33, it ispossible to change the position of the high illuminance region.

Further, in the headlight module 100, the shape of the cutoff line 91can be arbitrarily defined by the shape of the edge 321 of the emittingsurface 32 of the light guide component 3. That is, an arbitrary lightdistribution pattern can be formed depending on the shape of the lightguide component 3.

Thus, in particular, for the condensing lens 2, projection lens 4, andthe like, their shapes or the like need not be changed between modules.It is possible to use the condensing lens 2, projection lens 4, and thelike as common parts, thereby reducing the number of types of parts,improving ease of assembly, and reducing manufacturing cost.

Further, it is enough that the function of arbitrarily adjusting thewidth and height of the light distribution and the function ofarbitrarily adjusting the light distribution can be provided by theheadlight module 100 as a whole. The optical components of the headlightmodule 100 include the condensing lens 2, light guide component 3, andprojection lens 4. That is, the functions can be shared by opticalsurfaces constituting the headlight module 100.

For example, the emitting surface 32 of the light guide component 3 orthe reflecting surface 33 may be formed into a curved surface shape tohave power and form a light distribution.

However, if the emitting surface 32 is given a curvature, the emissionposition of light varies in the optical axis direction. That is, theemission position of light on the emitting surface 32 shifts forward orbackward in the optical axis direction. Since the emitting surface 32 isconjugate to the irradiated surface 9, variation of the emissionposition of light in the optical axis direction may cause effects, suchas blur of a projected cutoff line.

Further, for the reflecting surface 33, it is not necessary that all thelight reaches the reflecting surface 33. Thus, if the reflecting surface33 is given a shape, limited light can provide an effect of the shape ofthe reflecting surface 33 to the light distribution pattern. That is,the amount of light that can contribute to formation of the lightdistribution pattern is limited. The amount of light that is reflectedat the reflecting surface 33 to provide an effect of the shape of thereflecting surface 33 to the light distribution pattern is limited.Thus, to provide an optical effect to all the light and easily changethe light distribution pattern, it is preferable to give power to theincident surface 31 and cause it to form a desired light distribution.Here, “desired light distribution” refers to, for example, a lightdistribution specified in road traffic rules or the like.

The headlight module 100 includes the light source 1, condensing lens 2,light guide component 3, and projection lens 4. The light source 1 emitslight having directivity that becomes illumination light. The condensinglens 2 concentrates light emitted from the light source 1. The lightguide component 3 receives light emitted from the condensing lens 2through the incident surface 31, reflects the received light at thereflecting surface 33 formed on the side surface, and emits it from theemitting surface 32. The projection lens 4 receives light emitted fromthe light guide component 3 and magnifies and emits it. The incidentsurface 31 is formed by a curved surface for changing the divergenceangle of the incident light.

The headlight module 100 includes the light source 1, light guideelement 3, and projection optical element 4. The light source 1 emitslight. The light guide element 3 has the reflecting surface 33 forreflecting light emitted from the light source 1 and the emittingsurface 32 for emitting light reflected at the reflecting surface 33.The projection optical element 4 projects light emitted from theemitting surface 32. In the direction of the optical axis of theprojection optical element 4, the edge portion 321 of the reflectingsurface 33 on the emitting surface 32 side includes the point Q locatedat a focal position of the projection optical element 4.

In the first embodiment, as an example, the light guide element 3 isdescribed as the light guide component 3. Further, as an example, theprojection optical element 4 is described as the projection lens 4.Further, as an example, the edge portion 321 is described as the edge321.

Light entering the light guide element 3 and reaching the reflectingsurface 33 enters the light guide element 3 and undergoes the firstreflection at the reflecting surface 33.

Light undergoing the first reflection at the reflecting surface 33reaches the emitting surface 32 without undergoing further reflection.

In the headlight module 100, of the light entering the light guideelement 3, light reflected at the reflecting surface 33 and light otherthan the light reflected at the reflecting surface 33 are superposed ona plane passing through the point Q located at the focal position on theedge portion 321 and being perpendicular to the optical axis of theprojection optical element 4, thereby forming a high luminous intensityregion on the plane.

The plane perpendicular to the optical axis of the projection opticalelement 4 is the emitting surface 32.

The light guide element 3 has the incident portion 31 for receivinglight emitted from the light source 1, the incident portion 31 havingrefractive power.

As an example, the incident portion 31 is described as the incidentsurface 31.

Light reflected at the reflecting surface 33 directly reaches theemitting surface 32.

The reflecting surface 33 is a total reflection surface.

The inside of the light guide element 3 is filled with refractivematerial.

First Modification Example

Further, in the headlight module 100 according to the first embodimentof the present invention, each of the optical axes of the light source1, condensing lens 2, light guide component 3, and projection lens 4 isarranged in parallel with the z axis. However, such an arrangement isnot mandatory.

The light source 1 is located on the −z axis side (in back) of the lightguide component 3. The light source 1 is located on the +y axis side(upper side) of the light guide component 3.

The condensing lens 2 is located on the −z axis side (in back) of thelight guide component 3. The condensing lens 2 is located on the +y axisside (upper side) of the light guide component 3.

FIG. 10 is a configuration diagram illustrating a configuration of theheadlight module 100 according to the first embodiment. For example, asillustrated in FIG. 10, optical axes of the light source 1 andcondensing lens 2 may be arranged to be inclined in the −y axisdirection. “Optical axes are inclined in the −y axis direction”indicates that when viewed from the +x axis direction, the optical axesare rotated clockwise about the x axis. That is, it indicates that theend portions on the −z axis side of the optical axes are located in the+y axis direction from the end portions on the +z axis side of the axes.

In FIG. 10, with respect to the reflecting surface 33, the light source1 and condensing lens 2 are located on a light reflecting side of thereflecting surface 33. That is, with respect to the reflecting surface33, the light source 1 and condensing lens 2 are located on the frontsurface side of the reflecting surface 33. The light source 1 andcondensing lens 2 are located in a normal direction of the reflectingsurface 33 and on the front surface side of the reflecting surface 33with respect to the reflecting surface 33. The condensing lens 2 isdisposed to face the reflecting surface 33.

In FIG. 10, the optical axis of the light source 1 coincides with theoptical axis of the condensing lens 2. In FIG. 10, the optical axes ofthe light source 1 and condensing lens 2 have an intersection on thereflecting surface 33. When light is refracted at the incident surface31, a central light ray emitted from the condensing lens 2 reaches thereflecting surface 33. That is, the optical axis or central light ray ofthe condensing lens 2 has an intersection on the reflecting surface 33.

The arrangement illustrated in FIG. 10 makes it possible to reduce thelength of the light guide component 3 in an optical axis direction (zaxis direction), and shorten the depth (length in the z axis direction)of an optical system. Here, “optical system” refers to an optical systemincluding, as its components, the condensing lens 2, light guidecomponent 3, and projection lens 4.

Further, it becomes easy to guide light emitted from the condensing lens2 to the reflecting surface 33. Thus, it becomes easy to efficientlyconcentrate light at a region on the inner side of the edge 321 of theemitting surface 32. By concentrating light emitted from the condensinglens 2 at a region on the emitting surface 32 side of the reflectingsurface 33, it is possible to increase the emission amount of lightemitted from a region on the +y axis side of the edge 321.

In this case, the intersection between the optical axis of thecondensing lens 2 and the reflecting surface 33 is located on theemitting surface 32 side of the reflecting surface 33. In anotheraspect, the intersection between the central light ray emitted from thecondensing lens 2 and the reflecting surface 33 is located on theemitting surface 32 side of the reflecting surface 33.

Thus, it becomes easy to brighten a region on the lower side of thecutoff line 91 of the light distribution pattern projected on theirradiated surface 9. Further, the reduction in the length of the lightguide component 3 in the optical axis direction (z axis direction)reduces internal absorption of light in the light guide component 3,improving the light use efficiency. “Internal absorption” refers tolight loss inside the material excepting loss due to surface reflectionwhen light passes through the light guide component. The internalabsorption increases as a length of the light guide component increases.

A light beam entering the light guide element 3 from the light source 1is on the front surface side of the reflecting surface 33, and a centrallight ray of the light beam has an intersection on a plane including thereflecting surface 33.

In the first embodiment, as an example, the light guide element 3 isdescribed as the light guide component 3. Further, in the firstembodiment, as an example, the light beam entering the light guideelement 3 from the light source 1 enters through the incident surface31. The front surface of the reflecting surface 33 is a surface forreflecting light.

The light beam entering the light guide element 3 from the light source1 is on the front surface side of the reflecting surface 33, and travelstoward the reflecting surface 33.

Second Modification Example

Further, in the headlight module 100 according to the first embodimentof the present invention, the emitting surface 232 of the condensinglens 2 is parallel to a plane perpendicular to the optical axis of thecondensing lens 2. However, the shape of the emitting surface 232 is notlimited to such a shape.

FIGS. 11(A) and 11(B) are diagrams illustrating shapes of the condensinglens 2. FIG. 12 is a configuration diagram illustrating a configurationof the headlight module 100.

For example, as illustrated in FIGS. 11(A) and 11(B), the whole or apart of the emitting surface 232 may be inclined with respect to a planeperpendicular to the optical axis.

In FIG. 11(A), the emitting surface 232 of the condensing lens 2 isformed on the same plane. The emitting surface 232 on the same plane isinclined by an angle b with respect to the optical axis of thecondensing lens 2. The emitting surface 232 of FIG. 11(A) is inclined toface in the −y axis direction. That is, when viewed from the +x axisdirection, the emitting surface 232 is rotated clockwise about the xaxis. The dashed line in FIG. 11(A) represents a plane parallel to anx-y plane. That is, the dashed line in FIG. 11(A) represents a planeperpendicular to the optical axis of the condensing lens 2.

In FIG. 11(B), the emitting surface 232 of the condensing lens 2 is notformed on the same plane. The emitting surface 232 has regions 232 _(a)and 232 _(b).

The region 232 _(a) is formed by a flat surface perpendicular to theoptical axis of the condensing lens 2.

The region 232 _(a) is, for example, a region of the emitting surface232 on the +y axis side of the optical axis of the condensing lens 2.

The region 232 _(a) will be described in a more limited way. if theregion 232 _(a) is a flat surface perpendicular to the optical axis ofthe condensing lens 2, light emitted from the region 232 _(a) reachesthe front surface side of the reflecting surface 33. Light reflected atthe front surface of the reflecting surface 33 is emitted from theemitting surface 32. Further, light emitted from the emitting surface232 _(a) reaches the incident surface 31.

The front surface of the reflecting surface 33 is a surface forreflecting light of the reflecting surface 33. In the direction of aperpendicular line to the reflecting surface 33, the front surface ofthe reflecting surface 33 is a surface on the side on which thecondensing lens 2 is located.

On the other hand, the region 232 _(b) is formed by a flat surfaceinclined by an angle c with respect to a plane perpendicular to theoptical axis.

The region 232 _(b) is, for example, a region of the emitting surface232 on the −y axis side of the optical axis of the condensing lens 2.

The region 232 _(b) will be described in a more limited way. If theregion 232 _(b) is a flat surface perpendicular to the optical axis ofthe condensing lens 2, light emitted from the region 232 _(b) reachesthe back surface side of the reflecting surface 33. If the region 232_(b) is a flat surface perpendicular to the optical axis of thecondensing lens 2, light emitted from the region 232 _(b) reaches theback surface side of the reflecting surface 33. Further, light emittedfrom the emitting surface 232 _(a) does not reach the incident surface31.

The back surface of the reflecting surface 33 is a back surface of areflecting surface of the reflecting surface 33. In the direction of aperpendicular line to the reflecting surface 33, the back surface of thereflecting surface 33 is a surface on the opposite side of thecondensing lens 2.

The region 232 _(b) on the −y axis side of the emitting surface 232 isinclined to face in the −y axis direction. That is, when viewed from the+x axis direction, the region 232 _(b) on the −y axis side of theemitting surface 232 is rotated clockwise by the angle c about the xaxis. The dashed line in FIG. 11(B) represents a plane parallel to anx-y plane. That is, the dashed line in FIG. 11(B) represents a planeperpendicular to the optical axis of the condensing lens 2.

For example, if the respective optical axes of the light source 1 andcondensing lens 2 are arranged to be inclined in the −y axis directionwith respect to the z axis, as in the first modification example, it isdifficult to cause all of the light emitted from the emitting surface232 located at the lower end portion (end portion on the −y axis side)of the condensing lens 2 to enter the light guide component 3.

This is because, for example, in the case of FIG. 10, the position inthe y axis direction of the end portion on the −y axis direction side ofa region corresponding to the region 232 _(b) is located on the −y axisdirection side of the position in the y axis direction of the endportion on the −z axis direction side of the reflecting surface 33.“Emitting surface 232 located at the lower end portion (end portion onthe −y axis side) of the condensing lens 2” refers to a regioncorresponding to the region 232 _(b) illustrated in FIG. 12.

However, as illustrated in FIG. 12, by inclining the region 232 _(b) atthe lower end portion (−y axis direction) of the emitting surface 232 ofthe condensing lens 2, light is refracted in the +y axis direction.

That is, a light concentration position of light emitted from the region232 _(b) is shorter than a light concentration position of light emittedfrom the region 232 _(a). “Light concentration position” refers to aposition at which a light beam emitted from an emitting surface issmallest.

That is, a light concentration position of light emitted from theemitting surface 232 (region 232 _(a)) located on the front surface sideof the reflecting surface 33 of the emitting surface 232 of thecondensing lens 2 is farther from the condensing lens 2 than a lightconcentration position of light emitted from the emitting surface 232(region 232 _(b)) located on the back surface side of the reflectingsurface 33 of the emitting surface 232 of the condensing lens 2.

A light concentration position of light emitted from the side (region232 _(a)) far from the reflecting surface 33 with respect to the opticalaxis of the condensing lens 2 of the emitting surface 232 of thecondensing lens 2 is farther from the condensing lens 2 than a lightconcentration position of light emitted from the side (region 232 _(b))near the reflecting surface 33 with respect to the optical axis of thecondensing lens 2 of the emitting surface 232 of the condensing lens 2.

By providing the region 232 _(b), it is possible to cause light, whichwould not enter the light guide component 3 if the region 232 _(b) werenot provided, to enter the light guide component 3. Thus, it is possibleto improve the light use efficiency.

The region 232 _(b) of the second modification example is rotatedclockwise by the angle c about an axis parallel to the x axis, as viewedfrom the +x axis direction. However, this is not mandatory, and theregion 232 _(b) may be rotated counterclockwise about an axis parallelto the x axis, as viewed from the +x axis direction.

For example, suppose that the position in the y axis direction of theend portion on the −y axis direction side of the region 232 _(b) islocated on the +y axis direction side of the position in the y axisdirection of the end portion on the −z axis direction side of thereflecting surface 33. That is, suppose that the end portion on the −yaxis direction side of the region 232 _(b) is located on the +y axisdirection side of the end portion on the −z axis direction side of thereflecting surface 33.

To irradiate the reflecting surface 33 with a large amount of light toimprove the light use efficiency, the region 232 _(b) needs to berotated counterclockwise about an axis parallel to the x axis, as viewedfrom the +x axis direction. This is because light is refracted in the −yaxis direction when exiting the region 232 _(b), and thus a large amountof light reaches the reflecting surface 33.

The headlight module 100 includes the condensing element 2 forconcentrating light emitted from the light source 1. Of the light beamentering the light guide element 3 from the condensing element 2, in anormal direction of the reflecting surface 33, a focal length of thecondensing element 2 with respect to a first light ray at the end on thefront surface side of the reflecting surface 33 is longer than a focallength of the condensing element 2 with respect to a second light ray atthe end on the side opposite to the first light ray.

In the first embodiment, as an example, the light guide element 3 isdescribed as the light guide component 3. Further, as an example, thecondensing element 2 is described as the condensing lens 2. Further, asan example, the light beam entering the light guide element 3 from thelight source 1 enters through the incident surface 31.

In the first embodiment, the normal direction of the reflecting surface33 is described as the y axis direction. However, as illustrated in FIG.13B, if the reflecting surface 33 is inclined, the normal direction isalso inclined with respect to the y axis.

In the first embodiment, the front surface of the reflecting surface 33is a surface for reflecting light. The front surface side of thereflecting surface 33 is described as the +y axis direction side.Further, in the second modification example, the first light ray isdescribed as a light ray emitted from an end portion on the +y axis sideof the region 232 _(a). The second light ray is described as a light rayemitted from an end portion on the −y axis side of the region 232 _(b).

Third Modification Example

Further, in the headlight module 100 according to the first embodimentof the present invention, the reflecting surface 33 of the light guidecomponent 3 is a flat surface parallel to an x-z plane. However, thereflecting surface 33 is not limited to a flat surface parallel to anx-z plane.

FIGS. 13(A) and 13(B) are diagrams illustrating a comparison of shapebetween the light guide component 3 and a light guide component 35 ofthe headlight module 100 according to the first embodiment. FIG. 13(A)illustrates the above-described light guide component 3 for comparison.FIG. 13(B) illustrates the light guide component 35 of a thirdmodification example.

The reflecting surface 33 of the light guide component 35 illustrated inFIG. 13(B) is not a surface parallel to a z-x plane. For example, asillustrated in FIG. 13(B), the reflecting surface 33 may be a flatsurface inclined with respect to a z-x plane with the x axis as arotational axis.

The reflecting surface 33 of the light guide component 35 is a surfacerotated clockwise about the x axis, as viewed from the +x axisdirection. In FIG. 13(B), the reflecting surface 33 is a surface rotatedby an angle e with respect to a z-x plane. That is, the end portion onthe incident surface 31 side of the reflecting surface 33 is located onthe +y axis side of the end portion on the emitting surface 32 side.

The reflecting surface 33 of the light guide component 3 illustrated inFIG. 13(A) is a flat surface parallel to an x-z plane. Light enteringthrough the incident surface 31 is reflected at the reflecting surface33 and emitted from the emitting surface 32. The incident angle of thelight on the reflecting surface 33 is an incident angle S₁. Thereflection angle of the light at the reflecting surface 33 is areflection angle S₂. A perpendicular line m₁ to the reflecting surface33 is indicated by a dot-and-dash line in FIG. 13(A). According to thelaw of reflection, the reflection angle S₂ is equal to the incidentangle S₁.

Light is incident on the emitting surface 32 at an incident angle S₃.The light is emitted from the emitting surface 32 at an emission angleS_(out1). A perpendicular line m₂ to the emitting surface 32 isindicated by a dot-and-dash line in FIG. 13(A). According to Snell'slaw, the relationship between the incident angle S₃ and the emissionangle S_(out1) is given by the following formula (1):

n·sin S ₃=sin S _(out1)  (1)

where the symbol n is the refractive index of the light guide component3. The refractive index n is typically greater than 1. “·” used in theformula (1) denotes “multiplication.”

Since the light is greatly refracted at the incident surface 31, theemission angle S_(out1) of the light emitted from the emitting surface32 is great. As the emission angle S_(out1) becomes greater, theaperture of the projection lens 4 becomes larger. This is because, ifthe emission angle S_(out1) is great, the projection lens 4 needs toreceive light incident from a position far from the optical axis.

On the other hand, the reflecting surface 33 of the light guidecomponent 35 illustrated in FIG. 13(B) is inclined with respect to anx-z plane. The inclination direction of the reflecting surface 33 is theclockwise rotation direction with respect to an x-z plane as viewed fromthe +x axis direction.

That is, the reflecting surface 33 is inclined with respect to thetraveling direction (+z axis direction) of light in a direction suchthat an optical path in the light guide component 35 becomes wider. Thereflecting surface 33 is inclined so that the optical path in the lightguide component 35 becomes wider in the traveling direction (+z axisdirection) of light. Here, the traveling direction of light is thetraveling direction of light in the light guide component 35. Thus, thetraveling direction of light is the direction parallel to the opticalaxis of the light guide component 35.

In the direction of the optical axis of the light guide component 35,the reflecting surface 33 faces toward the emitting surface 32. “Facetoward the emitting surface 32” indicates that the reflecting surface 33can be seen from the emitting surface 32 side (+z axis direction side).

Light entering through the incident surface 31 is reflected at thereflecting surface 33 and emitted from the emitting surface 32. Theincident angle of the light on the reflecting surface 33 is an incidentangle S₄. The reflection angle of the light at the reflecting surface 33is a reflection angle S₅. A perpendicular line m₃ to the reflectingsurface 33 is indicated by a dot-and-dash line in FIG. 13(B). Accordingto the law of reflection, the reflection angle S₅ is equal to theincident angle S₄.

The light is incident on the emitting surface 32 at an incident angleS₆. The light is emitted from the emitting surface 32 at an emissionangle S_(out2). A perpendicular line m₄ to the emitting surface 32 isindicated by a dot-and-dash line in FIG. 13(B). According to Snell'slaw, the relationship between the incident angle S₆ and the emissionangle S_(out2) is given by the following formula (2):

n·sin S ₆=sin S _(out2)  (2)

where the symbol n is the refractive index of the light guide component35. The refractive index n is typically greater than 1. “·” used in theformula (2) denotes “multiplication.”

The incident angle S₄ is greater than the incident angle S₁ because ofthe inclination of the reflecting surface 33. Further, the reflectionangle S₅ is greater than the reflection angle S₂. Thus, the incidentangle S₆ is less than the incident angle S₃. The relationships betweenthe incident angles S₃ and S₆ and the emission angles S_(out1) andS_(out2) when the light is refracted at the emitting surface 32 obeysSnell's law. Since the refractive indexes n of the light guidecomponents 3 and 35 are equal to each other, the emission angle S_(out2)is less than the emission angle S_(out1).

To make the emission angle S_(out2) less than the emission angleS_(out1), it is also possible to form the reflecting surface 33 into acurved surface shape. Specifically, the reflecting surface 33 is formedby a curved surface such that the optical path becomes wider in thetraveling direction (+z axis direction) of light.

In the direction of the optical axis of the light guide component 35,the reflecting surface 33 is formed by a curved surface facing towardthe emitting surface 32.

The inclination of the reflecting surface 33 functions to decrease theemission angle Sow at which light reflected at the reflecting surface 33is emitted from the emitting surface 32. Thus, the inclination of thereflecting surface 33 can reduce the aperture of the projection lens 4,downsizing the headlight module 100. In particular, it contributes tothinning the headlight module 100 in the height direction (y axisdirection).

Further, by changing the angle of inclination of the reflecting surface33, it is possible to change the position of the high illuminanceregion.

In the direction of the optical axis of the projection optical element4, the reflecting surface 33 is inclined to face toward the emittingsurface 32.

As an example, the projection optical element 4 is described as theprojection lens 4.

Fourth Modification Example

Further, the first embodiment of the present invention describes a casewhere the single headlight module 100 includes the single light source 1and the single condensing lens 2. However, the number of sets of thelight source 1 and condensing lens 2 in a single headlight module is notlimited to one. In the following description, a light source 1 and acondensing lens 2 will be collectively referred to as a light sourcemodule 15.

FIG. 14 is a configuration diagram illustrating a configuration of aheadlight module 110 according to the first embodiment. FIG. 14 is adiagram of the headlight module 110 as viewed from the +y axisdirection.

For example, the headlight module 110 illustrated in FIG. 14 includesthree light source modules 15 _(a), 15 _(b), and 15 _(c). The lightsource modules 15 _(a), 15 _(b), and 15 _(c) include light sources 1_(a), 1 _(b), and 1 _(c) and condensing lenses 2 _(a), 2 _(b), and 2_(c), respectively. In FIG. 14, the three light source modules 15 arethe light source module 15 _(a), light source module 15 _(b), and lightsource module 15 _(c).

When viewed from the y axis direction, the light source 1 _(a) andcondensing lens 2 _(a) are disposed on the optical axes of the lightguide component 3 and projection lens 4. The light source 1 _(a) andcondensing lens 2 _(a) constitute the light source module 15 _(a).

Further, the light source 1 _(b) is disposed on the −x axis side of thelight source 1 _(a). The condensing lens 2 _(b) is disposed on the −xaxis side of the condensing lens 2 _(a). The light source 1 _(b) andcondensing lens 2 _(b) constitute the light source module 15 _(b). Thatis, the light source module 15 _(b) is disposed on the −x axis side ofthe light source module 15 _(a).

Further, the light source 1 _(c) is disposed on the +x axis side of thelight source 1 _(a). The condensing lens 2 _(c) is disposed on the +xaxis side of the condensing lens 2 _(a). The light source 1 _(c) andcondensing lens 2 _(c) constitute the light source module 15 _(c). Thatis, the light source module 15, is disposed on the +x axis side of thelight source module 15 _(a).

Light emitted from the light source 1 _(a) passes through the condensinglens 2 _(a) and enters the light guide component 3 through the incidentsurface 31. When viewed from the y axis direction, a position in the xaxis direction at which the light is incident on the incident surface 31coincides with a position of the optical axis of the light guidecomponent 3. The incident light is reflected at the reflecting surface33 and emitted from the emitting surface 32. When viewed from the y axisdirection, a position in the x axis direction at which the light isemitted from the emitting surface 32 coincides with a position of theoptical axis of the light guide component 3.

Light emitted from the light source 1 _(b) passes through the condensinglens 2 _(b) and enters the light guide component 3 through the incidentsurface 31. When viewed from the y axis direction, a position in the xaxis direction at which the light is incident on the incident surface 31is on the −x axis side of the optical axis of the light guide component3. The incident light is reflected at the reflecting surface 33 andemitted from the emitting surface 32. When viewed from the y axisdirection, a position in the x axis direction at which the light isemitted from the emitting surface 32 is on the +x axis side of theoptical axis of the light guide component 3.

Light emitted from the light source 1 _(c) passes through the condensinglens 2 _(c) and enters the light guide component 3 through the incidentsurface 31. When viewed from the y axis direction, a position in the xaxis direction at which the light is incident on the incident surface 31is on the +x axis side of the optical axis of the light guide component3. The incident light is reflected at the reflecting surface 33 andemitted from the emitting surface 32. When viewed from the y axisdirection, a position in the x axis direction at which the light isemitted from the emitting surface 32 is on the −x axis side of theoptical axis of the light guide component 3.

Thus, the configuration illustrated in FIG. 14 can spread the light beamemitted from the emitting surface 32 in the horizontal direction (x axisdirection). Since the emitting surface 32 and irradiated surface 9 arein conjugate relation with each other, the headlight module 110 canincrease the width of the light distribution pattern in the horizontaldirection.

Such a configuration makes it possible to increase the amount of lightwithout providing multiple headlight modules 100. That is, the headlightmodule 110 contributes to downsizing of the entire headlight device.Further, the headlight module 110 can easily achieve a lightdistribution wide in the horizontal direction (x axis direction).

Further, in FIG. 14, the multiple light source modules 15 are arrangedin the horizontal direction (x axis direction). However, the multiplelight source modules 15 may be arranged in the vertical direction (yaxis direction). For example, light source modules 15 are arranged intwo levels in the y axis direction. This makes it possible to increasethe amount of light of the headlight module 110.

Further, by performing control for individually turning on or off thelight sources 1 _(a), 1 _(b), and 1 _(c), it is possible to select anilluminated area in front of the vehicle. Thus, it is possible toprovide the headlight module 110 with a light distribution changefunction. That is, the headlight module 110 can have a function ofchanging the light distribution.

For example, when a vehicle turns right or left at an intersection, alight distribution wider in the direction in which the vehicle turnsthan the light distribution of a typical low beam is required. In such acase, by performing control for individually turning on or off the lightsources 1 _(a), 1 _(b), and 1 _(c), it is possible to obtain an optimumlight distribution corresponding to the traveling situation. The drivercan obtain better visibility in the traveling direction by changing thelight distribution of the headlight module 110.

Second Embodiment

FIG. 15 is a configuration diagram illustrating a configuration of aheadlight module 120 according to a second embodiment of the presentinvention. Elements that are the same as in FIG. 1 will be given thesame reference characters, and descriptions thereof will be omitted. Theelements that are the same as in FIG. 1 are the light source 1,condensing lens 2, light guide component 3, and projection lens 4.

As illustrated in FIG. 15, the headlight module 120 according to thesecond embodiment includes the light source 1, light guide component 3,projection lens 4, a rotation mechanism 5, and a control circuit 6. Theheadlight module 120 may include the condensing lens 2.

The rotation mechanism 5 rotates the light guide component 3 andprojection lens 4 as a unit about an optical axis. That is, theheadlight module 120 according to the second embodiment differs from theheadlight module 100 according to the first embodiment in having therotation mechanism 5 and control circuit 6.

<Tilt of Vehicle Body and Tilt of Light Distribution Pattern>

In general, when a motorcycle corners, the vehicle body tilts. When thevehicle body of the motorcycle tilts, the headlight device tiltstogether with the vehicle body. Thus, there is a problem that a cornerarea toward which the driver's gaze is directed is not sufficientlyilluminated.

“Corner area” refers to an illumination area in the traveling directionof the vehicle when the vehicle is turning. The corner area is an areain the traveling direction toward which the driver's gaze is directed.Typically, when the vehicle turns left, the corner area is an area onthe left side of an illumination area when the vehicle travels straight.Further, when the vehicle turns right, the corner area is an area on theright side of the illumination area when the vehicle travels straight.

FIGS. 16(A) and 16(B) are schematic diagrams illustrating lightdistribution patterns 103 and 104 of the motorcycle. FIG. 16(A)illustrates the light distribution pattern 103 in a situation where themotorcycle travels without tilting the vehicle body. That is, FIG. 16(A)illustrates the light distribution pattern 103 in a situation where themotorcycle travels straight. FIG. 16(B) illustrates the lightdistribution pattern 104 in a situation where the motorcycle travelswhile tilting the vehicle body to the left. That is, FIG. 16(B)illustrates the light distribution pattern 104 in a situation where themotorcycle turns left.

In FIGS. 16(A) and 16(B), the motorcycle is traveling in a left lane.The line H-H represents the horizon line. The line V-V represents a lineperpendicular to the line H-H (horizon line) at a position of thevehicle body. Since the motorcycle travels in the left lane, the centerline 102 is located on the right side of the line V-V. Further, thelines 101 represent parts of the left edge and right edge of the roadsurface. The motorcycle illustrated in FIG. 16(B) is cornering whiletilting the vehicle body to the left by a tilt angle d with respect tothe line V-V. The tilt angle d of the vehicle body relative to the lineV-V of the motorcycle is referred to as the bank angle.

The light distribution pattern 103 illustrated in FIG. 16(A) is wide inthe horizontal direction and illuminates a predetermined area withoutwaste. However, the light distribution pattern 104 illustrated in FIG.16(B) is radiated while being tilted in such a manner that the left sideis down and the right side is up. At this time, an area in the travelingdirection toward which the driver's gaze is directed is a corner area105. “Predetermined” here refers to, for example, being specified byroad traffic rules or the like.

In FIG. 16(B), the corner area 105 is on the left side of the line V-Vand in contact with the line H-H below the line H-H. In FIG. 16(B), thecorner area 105 is represented by a dashed line.

A typical headlight device is fixed to a vehicle body. Thus, when thevehicle corners, on the road (in FIG. 16, left side) in the travelingdirection, the headlight device illuminates an area below the roadsurface. Thus, the corner area 105 is not sufficiently illuminated andis dark.

Further, when the vehicle corners, on the road (in FIG. 16, right side)in a direction opposite to the traveling direction, the typicalheadlight device illuminates a position above the road surface. Thus,the headlight device may illuminate an oncoming vehicle with dazzlinglight.

FIG. 17 is an explanatory diagram illustrating the tilt angle d of thevehicle body. FIG. 17 is a schematic diagram illustrating a state inwhich the vehicle body of the motorcycle 94 is tilted, as viewed fromthe front of the motorcycle 94. FIG. 17 illustrates a state in which themotorcycle 94 is tilted by the tilt angle d to the right with respect tothe traveling direction.

In FIG. 17, the motorcycle 94 is tilted by the tilt angle d to the rightwith respect to the traveling direction. That is, the motorcycle 94rotates to the left or right about a position 98 at which a wheel 95makes contact with the ground.

In FIG. 17, the motorcycle 94 is rotated counterclockwise by the angle dabout the position 98 at which the wheel 95 makes contact with theground, as viewed from the +z axis direction. In this case, it can beseen that the headlight device 250 is also tilted by the tilt angle d.

The headlight module 120 according to the second embodiment solves sucha problem with small and simple structure.

<Configuration of Headlight Module 120>

As illustrated in FIG. 15, the rotation mechanism 5 of the headlightmodule 120 according to the second embodiment supports the light guidecomponent 3 and projection lens 4 rotatably about an optical axis.

The rotation mechanism 5 includes, for example, a stepping motor 51,gears 52, 53, 54, and 55, and a shaft 56. The stepping motor 51 may bereplaced with, for example, a DC motor or the like.

The control circuit 6 sends a control signal to the stepping motor 51.The control circuit 6 controls a rotation angle and a rotation speed ofthe stepping motor 51.

The control circuit 6 is connected to a vehicle body tilt sensor 65 fordetecting the tilt angle d of the motorcycle 94. The vehicle body tiltsensor 65 is, for example, a sensor, such as a gyro, or the like. Thecontrol circuit 6 receives a signal of the tilt angle d of the vehiclebody detected by the vehicle body tilt sensor 65. The control circuit 6performs calculation based on the detected signal to control thestepping motor 51.

If the motorcycle 94 is tilted by the tilt angle d, the control circuit6 rotates the light guide component 3 and projection lens 4 by the angledin a direction opposite to the tilt direction of the vehicle body. Thatis, the direction in which the light guide component 3 and projectionlens 4 is rotated is opposite to the tilt direction of the vehicle body.

The gear 53 is mounted on the light guide component 3 so that arotational axis of the gear 53 coincides with the optical axis of thelight guide component 3 and the gear 53 surrounds the light guidecomponent 3. That is, the rotational axis of the gear 53 coincides withthe optical axis of the light guide component 3. Further, the gear 53 isdisposed around the light guide component 3. In FIG. 15, the gear 53 isdisposed to surround the light guide component 3. However, the gear 53may be disposed at a part of the circumference of the light guidecomponent 3.

The gear 55 is mounted on the projection lens 4 so that a rotationalaxis of the gear 55 coincides with the optical axis of the projectionlens 4 and the gear 55 surrounds the projection lens 4. That is, therotational axis of the gear 55 coincides with the optical axis of theprojection lens 4. Further, the gear 55 is disposed around theprojection lens 4. In FIG. 15, the gear 55 is disposed to surround theprojection lens 4. However, the gear 55 may be disposed at a part of thecircumference of the projection lens 4.

The shaft 56 coincides with a rotational axis of the stepping motor 51.The shaft 56 is also mounted to a rotation shaft of the stepping motor51. The shaft 56 is disposed in parallel with the optical axis of thelight guide component 3 and the optical axis of the projection lens 4.

A rotational axis of the gear 52 coincides with the shaft 56. The gear52 is mounted on the shaft 56. The gear 52 meshes with the gear 53.

A rotational axis of the gear 54 coincides with the shaft 56. The gear54 is mounted on the shaft 56. The gear 54 meshes with the gear 55.

Since the rotation mechanism 5 is configured in this manner, as therotation shaft of the stepping motor 51 rotates, the shaft 56 rotates.As the shaft 56 rotates, the gears 52 and 54 rotate. As the gear 52rotates, the gear 53 rotates. As the gear 53 rotates, the light guidecomponent 3 rotates about the optical axis. As the gear 54 rotates, thegear 55 rotates. As the gear 55 rotates, the projection lens 4 rotatesabout the optical axis.

Since the gears 52 and 54 are mounted on the single shaft 56, the lightguide component 3 and projection lens 4 rotate simultaneously. The lightguide component 3 and projection lens 4 also rotate in the samedirection.

The rotation mechanism 5 rotates the light guide component 3 andprojection lens 4 based on a control signal obtained from the controlcircuit 6. The direction in which the light guide component 3 andprojection lens 4 are rotated is a direction opposite to the tiltdirection of the vehicle body. The tilt direction of the vehicle body isalso referred to as the “bank direction.”

The rotation angles of the light guide component 3 and projection lens 4depend on the numbers of teeth of the gears 52, 53, 54, and 55. If therotation angles of the light guide component 3 and projection lens 4 areset to be equal to each other, the rotation mechanism 5 can rotate thelight guide component 3 and projection lens 4 as a unit.

The emitting surface 32 of the light guide component 3 can be treated asa secondary light source. “Secondary light source” refers to a surfacelight source that emits planar light.

Further, the emitting surface 32 is in an optically conjugate relationwith the irradiated surface 9.

Thus, if the light guide component 3 and projection lens 4 are rotatedabout the optical axis without changing the geometrical relation betweenthe light guide component 3 and the projection lens 4, the lightdistribution pattern illuminating the irradiated surface 9 is alsorotated by the same rotational amount as that of the light guidecomponent 3 and projection lens 4.

Thus, by rotating the light guide component 3 and projection lens 4 in adirection opposite to the tilt direction by the same amount as the tiltangle d, it is possible to correctly compensate the tilt of the lightdistribution pattern due to the tilt of the vehicle body of themotorcycle 94.

The rotation mechanism 5 is not limited to the above and may be otherrotation mechanisms. Stepping motors for rotating each of the lightguide component 3 and projection lens 4 may be provided to individuallycontrol their amounts of rotation. That is, a stepping motor for thelight guide component 3 and a stepping motor for the projection lens 4may be provided.

FIGS. 18(A) and 18(B) are schematic diagrams each illustrating a casewhere the light distribution pattern is corrected by the headlightmodule 120. FIG. 18(A) illustrates a case of cornering to the left whiletraveling in the left lane. FIG. 18(B) illustrates a case of corneringto the right while traveling in the left lane.

As described above, the control circuit 6 rotates the light distributionpattern 106 in accordance with the tilt angle d of the vehicle body. Thelight distribution pattern 106 in FIG. 18(A) is rotated by the tiltangle d clockwise as viewed in the traveling direction. The lightdistribution pattern 106 in FIG. 18(B) is rotated by the tilt angle dcounterclockwise as viewed in the traveling direction. Whether thevehicle body tilts to the left or right, the headlight module 120 canprovide the same light distribution pattern 106 as in the case where thevehicle body is not tilted, as a result.

In this manner, the headlight module 120 according to the secondembodiment rotates the light guide component 3 and projection lens 4 inaccordance with the tilt angle d of the vehicle body. Thereby, theformed light distribution pattern 106 rotates about an optical axis ofan optical system. The projection lens 4 magnifies and projects lightwith the rotated light distribution pattern 106.

Thereby, the headlight module 120 can illuminate an area (corner area105) in the traveling direction toward which the driver's gaze isdirected.

Further, since the light guide component 3 and projection lens 4, whichare relatively small as compared to conventional optical components, arerotated, it is possible to drive them with a small driving force, ascompared to a case of rotating a light source and a large lens that areprovided in a conventional headlight device.

Further, it becomes unnecessary to rotatably support a large-diameterlens. From these, the rotation mechanism 5 can be downsized.

Further, if a surface shape of the projection lens 4 is, for example, atoroidal lens having different curvatures in the x axis direction and yaxis direction, it is effective to rotate the projection lens 4 togetherwith the light guide component 3. The toroidal lens is a lens havingdifferent powers in the x axis direction and y axis direction. Byemploying the toroidal lens as the projection lens 4, the formation ofthe light distribution pattern can be shared with the light guidecomponent 3.

If the projection lens 4 has a function of sharing the formation of thelight distribution pattern with the light guide component 3, theprojection lens 4 is not limited to the toroidal lens and may be acylindrical lens or a lens having a free-form surface. The cylindricallens is a lens having refractive power to perform convergence ordivergence in one direction but having no refractive power in theorthogonal direction.

Further, in FIG. 15, a configuration in which the projection lens 4 isrotated is illustrated. However, a configuration in which the projectionlens 4 is not rotated may be employed.

The headlight module 120 includes the rotation mechanism 5 for rotatingthe light guide component 3 about an axis parallel to the optical axisand the controller 6. The controller 6 drives the rotation mechanism 5.

In a case where the projection lens 4 has the shape of a solid ofrevolution with the optical axis as the center, and the optical axis ofthe projection lens 4 coincides with the optical axis of the light guidecomponent 3 as described above, even if the configuration in which theprojection lens 4 is rotated is not employed, there is no particularproblem. “Solid of revolution” refers to a solid figure obtained byrotating a plane figure about a straight line (axis) on the same planeas the plane figure.

That is, if a lens surface of the projection lens 4 has a rotationallysymmetric surface shape and a center of curvature of the projection lens4 coincides with the optical axis of the light guide component 3, thesame advantages can be obtained by rotating only the light guidecomponent 3 about the optical axis without rotating the projection lens4. In this case, the optical axis of the projection lens 4 coincideswith the optical axis of the light guide component 3.

In this case, the gears 54 and 55 are unnecessary. That is, the rotationmechanism 5 can be further downsized and simplified, as compared to acase of rotating the light guide component 3 and projection lens 4 aboutthe optical axis as a unit.

Further, as described in the first modification example of the firstembodiment, the light source 1 and condensing lens 2 may be inclinedwith respect to the light guide component 3 and projection lens 4. Insuch a case, the light source 1 and condensing lens 2 need to be rotatedintegrally with the light guide component 3 about the rotational axis ofthe light guide component 3.

Further, as described in the fourth modification example of the firstembodiment, the headlight module may include the multiple light sourcemodules 15. Also in such a case, the light source modules 15 need to berotated integrally with the light guide component 3 about the rotationalaxis of the light guide component 3.

This is because, in these cases, if the light source 1 and condensinglens 2 are fixed, rotation of the light guide component 3 changes thecondition of light entering the light guide component 3, complicatingformation of the light distribution pattern.

The second embodiment rotates the light guide component 3 and projectionlens 4 about the optical axis. However, the light guide component 3 maybe rotated about an axis other than the optical axis. The projectionlens 4 may also be rotated about an axis other than the optical axis.

For example, for the light guide component 3, one end of the rotationalaxis may pass through the incident surface 31. Further, the other end ofthe rotational axis may pass through the emitting surface 32. In thismanner, an axis passing through the surfaces at both ends in the opticalaxis direction of the light guide component 3 may be set as therotational axis. That is, this rotational axis is inclined with respectto the optical axis of the light guide component 3.

Similarly, for example, for the projection lens 4, one end of therotational axis may pass through an incident surface (surface on the −zaxis side) of the projection lens 4. Further, the other end of therotational axis may pass through an emitting surface (surface on the +zaxis side) of the projection lens 4. In this manner, an axis passingthrough the surfaces at both ends in the optical axis direction of theprojection lens 4 may be set as the rotational axis. That is, thisrotational axis is inclined with respect to the optical axis of theprojection lens 4.

However, if the rotational axis coincides with the optical axis, sincethe rotational axis of the light distribution pattern can be set to theoptical axis, the light distribution can be controlled more easily.

Further, the headlight module 120 according to the second embodimentrotates the light guide component 3 and projection lens 4 about theoptical axis by the angle d in a direction opposite to the tiltdirection in accordance with the tilt angle d of the vehicle body.

However, this is not mandatory, and the rotation angle may be anarbitrary angle; for example, the light guide component 3 and projectionlens 4 may be rotated about the optical axis by an angle greater thanthe tilt angle d. Thus, the light distribution pattern can beintentionally tilted as necessary, instead of being always horizontal.

For example, by tilting the light distribution pattern so as to raisethe corner area 105 side of the light distribution, it is possible tomake it easy for the driver to observe an area in the travelingdirection of the vehicle. Further, in the case of a left hand corner, bytilting the light distribution pattern so as to lower a side opposite tothe corner area 105 side of the light distribution, it is possible toreduce dazzling of an oncoming vehicle due to projection light.

The second embodiment is described by taking the motorcycle 94 as anexample. However, for the above-described motor tricycle called gyro orthe like, most of the vehicle body including a front wheel and a driverseat is tilted in the left-right direction around a corner. Thus, theheadlight module 120 may be used in a motor tricycle.

The headlight module 120 may also be used in a four-wheeled vehicle. Forexample, when it corners to the left, the vehicle body tilts to theright. Further, when it corners to the right, the vehicle body tilts tothe left. This is due to centrifugal force. In this respect, it isopposite in the bank direction to a motorcycle. However, a four-wheeledvehicle may also detect the bank angle of the vehicle body to correctthe irradiated area. Further, when the vehicle body tilts because, forexample, only a wheel or wheels on one side drive over an obstacle orthe like, it is also possible to obtain the same irradiated area as whenthe vehicle body is not tilted.

The headlight module 120 includes the rotation mechanism 5 relative tothe headlight module 100. The rotation mechanism 5 rotates the lightguide element 3. The rotation mechanism 5 rotates the light guideelement 3 about an axis passing through an end portion of the lightguide element 3 on a side on which light emitted from the light source 1is incident and the emitting surface 32.

In the second embodiment, as an example, the light guide element 3 isdescribed as the light guide component 3. Further, as an example, theend portion on the side on which light is incident is described as theincident surface 31.

The rotation mechanism 5 can rotate the light guide element 3 about anaxis that passes through a surface passing through an end portion of thelight guide element 3 on a side on which light emitted from the lightsource 1 is incident and a surface passing through the emitting surface32. In another aspect, the rotation mechanism 5 can rotate the lightguide element 3 about an axis that passes through a surface including anend portion of the light guide element 3 on a side on which lightemitted from the light source 1 is incident and a surface including theemitting surface 32.

Further, in the second embodiment, the rotation mechanism 5 rotates thelight guide element 3 about the optical axis of the projection opticalelement 4.

Further, in the second embodiment, the rotation mechanism 5 rotates thelight guide element 3 about an axis passing through the end portion 321.

As an example, the end portion 321 is described as the edge 321.

The headlight module 120 includes the rotation means 5 relative to theheadlight module 100. The rotation means 5 rotates the light guideelement 3. The rotation means 5 rotates the light guide element 3 aboutan axis passing through an end portion of the light guide element 3 on aside on which light emitted from the light source 1 is incident and theemitting surface 32.

In the second embodiment, as an example, the light guide element 3 isdescribed as the light guide component 3. Further, as an example, theend portion on the side on which light is incident is described as theincident surface 31.

The rotation means 5 can rotate the light guide element 3 about an axisthat passes through a surface passing through an end portion of thelight guide element 3 on a side on which light emitted from the lightsource 1 is incident and a surface passing through the emitting surface32. In another aspect, the rotation means 5 can rotate the light guideelement 3 about an axis that passes through a surface including an endportion of the light guide element 3 on a side on which light emittedfrom the light source 1 is incident and a surface including the emittingsurface 32.

Further, in the second embodiment, the rotation means 5 rotates thelight guide element 3 about the optical axis of the projection opticalelement 4.

Further, in the second embodiment, the rotation means 5 rotates thelight guide element 3 about an axis passing through the end portion 321.

As an example, the rotation means 5 is described as the rotationmechanism 5.

Third Embodiment

FIG. 19 is a configuration diagram illustrating a configuration of aheadlight module 130 according to a third embodiment of the presentinvention. Elements that are the same as in FIG. 1 will be given thesame reference characters, and descriptions thereof will be omitted. Theelements that are the same as in FIG. 1 are the light source 1,condensing lens 2, light guide component 3, and projection lens 4.

As illustrated in FIG. 19, the headlight module 130 according to thethird embodiment includes the light source 1, the light guide component3, the projection lens 4, a translation mechanism 7, and the controlcircuit 6. The headlight module 130 may include the condensing lens 2.

“Translation” refers to parallel displacement of each point constitutinga rigid body or the like in the same direction. Hereinafter,“translation” will also be referred to as “translation.” Further, thedistance by which a component is translated will be referred to as the“translation amount.”

The translation mechanism 7 moves the projection lens 4 in the x axisdirection. That is, the headlight module 130 differs from the headlightmodule 100 according to the first embodiment in having the translationmechanism 7 and control circuit 6.

In headlight devices, a technique is known in which, when a vehiclecorners, the optical axis of its headlight device is controlled to bedirected in the traveling direction. In particular, in headlight devicesfor automobiles, an illuminating direction of a headlight device ismoved in the left-right direction (x axis direction) of the vehiclebased on information, such as a steering angle, vehicle speed, orvehicle height of the automobile. “Steering angle” refers to an angle ofsteering for arbitrarily changing the traveling direction of thevehicle. The “steering angle” is also referred to as the “steeringangle.”

However, a conventional headlight device typically employs a method ofturning the entire headlight. Thus, there is a problem that the driveunit is large. Further, there is a problem that the load of the driveunit is large.

The headlight module 130 according to the third embodiment of thepresent invention solves such problems. The headlight module 130 solvessuch problems with a small and simple structure.

As illustrated in FIG. 19, the translation mechanism 7 includes astepping motor 71, a pinion 72, a rack 73, and a shaft 76.

The translation mechanism 7 of the headlight module 130 according to thethird embodiment supports the projection lens 4 translatably in the xaxis direction, as illustrated in FIG. 19. The translation mechanism 7includes, for example, the stepping motor 71, pinion 72, rack 73, andshaft 76.

The translation mechanism 7 obtains a translation amount from thecontrol circuit 6. The translation mechanism 7 then translates theprojection lens 4 in the left-right direction based on the translationamount.

A shaft of the stepping motor 71 is connected to the shaft 76. The shaftof the stepping motor 71 and the shaft 76 are disposed in parallel withthe z axis. That is, the shaft of the stepping motor 71 and the shaft 76are disposed in parallel with the optical axis of the projection lens 4.

The pinion 72 is mounted on the shaft 76. An axis of the pinion 72 isparallel to the z axis. Teeth of the pinion 72 mesh with teeth of therack 73. The pinion 72 is disposed on the outer side of the rack 73 withrespect to the projection lens 4.

The rack 73 is mounted on the projection lens 4. The rack 73 is disposedon the upper side (+y axis direction side) of the projection lens 4, asviewed in a direction (+z axis direction) from the headlight module 130to the irradiated surface 9. Alternatively, the rack 73 may be disposedon the lower side (−y axis direction side) of the projection lens 4, asviewed in a direction (+z axis direction) from the headlight module 130to the irradiated surface 9.

The rack 73 is disposed in parallel with the x axis. That is, the rack73 is disposed so that the teeth of the rack 73 are aligned in thehorizontal direction (x axis direction).

The teeth of the rack 73 are formed on the outer side with respect tothe projection lens 4. That is, if the rack 73 is disposed on the upperside (+y axis direction side) of the projection lens 4, the teeth of therack 73 are formed on the upper side (+y axis direction side) of therack 73. If the rack 73 is disposed on the lower side (−y axis directionside) of the projection lens 4, the teeth of the rack 73 are formed onthe lower side (−y axis direction side) of the rack 73.

As the stepping motor 71 rotates, the shaft 76 rotates. As the shaft 76rotates, the pinion 72 rotates. That is, the pinion 72 rotates about theaxis of the pinion 72 due to the rotation of the shaft 76. As the pinion72 rotates, the rack 73 moves in the x axis direction. As the rack 73moves in the x axis direction, the projection lens 4 moves in the x axisdirection.

As described above, the translation mechanism 7 translates theprojection lens 4 in the left-right direction based on the translationamount obtained from the control circuit 6.

For example, the control circuit 6 is connected to a vehicle body statesensor 66. The vehicle body state sensor 66 is, for example, a steeringangle sensor, a vehicle speed sensor, or the like. “Steering anglesensor” refers to a sensor for sensing a steering angle of the frontwheel when a steering wheel is turned.

The control circuit 6 receives information, such as a steering angle,vehicle speed, or vehicle height of the vehicle body, detected by thevehicle body state sensor 66. The vehicle body state sensor 66 detects asteering angle, vehicle speed, vehicle height of the vehicle body, orthe like. The control circuit 6 performs calculation based on a signalof the steering angle, vehicle speed, vehicle height, or the like, andcontrols the stepping motor 71.

For example, it will be assumed that the projection lens 4 is a lensthat images the light distribution pattern on the emitting surface 32 ofthe light guide component 3 at a magnification of 1000 onto theirradiated surface 9 located 25 m ahead. In this case, if the projectionlens is translated by 2.0 mm from an optical axis center in the rightdirection (+x direction), the amount of movement of the optical axis at25 m ahead is 1000 mm. At this time, the amount of tilt of the opticalaxis in the +x axis direction is represented by the following formula(3):

tan⁻¹(1000 [mm]/25000 [mm])=2.29 [deg]  (3).

That is, in the above example, the tilt of the optical axis is 2.29degrees. That is, the headlight module 130 can tilt the optical axis byslightly translating the projection lens 4 in the left-right direction(x axis direction).

The control circuit 6 calculates the traveling direction of the vehiclebased on the information (signal) detected by the vehicle body statesensor 66. The control circuit 6 then controls the stepping motor 71 sothat an optical axis on the emitting surface 32 of the headlight module130 is directed in an optimum direction, and adjusts the amount of shiftof the projection lens 4 in the left-right direction. “Optical axis onthe emitting surface 32” refers to an optical axis of light projectedonto the irradiated surface 9.

FIGS. 20(A) and 20(B) are diagrams each illustrating an irradiated areawhen a vehicle with the headlight module 130 according to the thirdembodiment is cornering. FIG. 20(A) illustrates a situation where thevehicle is traveling in the left lane of a corner curved to the left.FIG. 20(B) illustrates a situation where the vehicle is traveling in theleft lane of a corner curved to the right.

In FIG. 20(A), the light distribution pattern 103 has been moved to theleft side in the horizontal direction (direction of the line H-H). Thecorner area 105 is located at a center of the light distribution pattern103. In FIG. 20(B), the light distribution pattern 103 has been moved tothe right side in the horizontal direction (direction of the line H-H).The corner area 105 is located at a center of the light distributionpattern 103.

As described above, the control circuit 6 can direct the lightdistribution pattern 103 in an optimum direction by tilting the opticalaxis of the light distribution pattern 103 in the horizontal directionin accordance with the steering angle of the vehicle or the like. InFIG. 20, the “horizontal direction” is the direction of the line H-H.

Thus, in the case of traveling in a curve, whether the curve is left orright hand, the control circuit 6 can direct the optical axis of thelight distribution pattern 103 to the corner area 105. The corner area105 is in a driver's gaze direction. Here, “optical axis of the lightdistribution pattern 103 refers to a center of the cutoff line of thelight distribution pattern 103 in the horizontal direction.

That is, in the case of traveling in a curve, whether the curve is leftor right hand, the control circuit 6 can direct the light distributionpattern 103 to the corner area 105, which is in a driver's gazedirection. By the control of the control circuit 6, the headlight module130 can illuminate the corner area 105 with a part having the highestilluminance of the light distribution pattern 103.

In this manner, the headlight module 130 according to the thirdembodiment translates the projection lens 4 by an optimum translationamount corresponding to the steering angle or the like of the vehicle.Thereby, when the vehicle turns a corner to the right or left, theheadlight module 130 can illuminate an area (corner area 105) towardwhich the driver's gaze is directed, with a part having the highestilluminance of the light distribution pattern 103.

The headlight module 130 slightly translates the projection lens 4 inthe left-right direction. Thus, the headlight module 130 can drive thedriven part (projection lens 4) with a small driving force, as comparedto a conventional case of rotating an illuminator (light source) and alarge-diameter lens that are provided in a lamp main body. Further,since the driven part (projection lens 4) is smaller than that of theconventional case, the structure for supporting the driven part can bemade small. Further, since the distance by which the projection lens 4is translated is small, the light distribution pattern 103 can be movedin a short time.

The headlight module 130 of the third embodiment translates theprojection lens 4 in the left-right direction (x axis direction)relative to the light guide component 3. However, as a method oftranslating the optical axis of the light distribution pattern in theleft-right direction with respect to the traveling direction of thevehicle as in the third embodiment, the following method may be used.For example, the same advantages can be obtained by a method of turningthe projection lens 4 in the left-right direction, i.e., a method ofrotating the projection lens 4 about an axis parallel to the y axis andpassing through the optical axis of the projection lens 4.

The headlight module 130 includes the translation mechanism 7 fortranslating the projection optical element 4 in a directionperpendicular to the optical axis of the projection optical element 4relative to the light guide element 3.

In the third embodiment, as an example, the light guide element 3 isdescribed as the light guide component 3. Further, as an example, theprojection optical element 4 is described as the projection lens 4.

The headlight module 130 includes the translation means 7 fortranslating the projection optical element 4 in a directionperpendicular to the optical axis of the projection optical element 4relative to the light guide element 3.

As an example, the translation means 7 is described as the translationmechanism 7.

<Modifications>

FIG. 21 is a configuration diagram illustrating a configuration of aheadlight module 140. The headlight module 140 rotates the projectionlens 4 about a shaft 57 parallel to the y axis and passing through anoptical axis.

The headlight module 140 includes the light source 1, the light guidecomponent 3, the projection lens 4, a rotation mechanism 50, and thecontrol circuit 6. The headlight module 140 may include the condensinglens 2.

The rotation mechanism 50 rotates the projection lens 4 about the shaft57.

The shaft 57 is a shaft parallel to the y axis and passing through theoptical axis of the projection lens 4. The shaft 57 is a shaft parallelto the y axis and perpendicular to the optical axis of the projectionlens 4. For simplicity, in FIG. 21, the shaft 57 is depicted to passthrough the projection lens 4 in the y axis direction. Actually, theshaft 57 is formed by a pin or the like projecting from an end portionin the y axis direction of the projection lens 4.

The stepping motor 51 rotates the shaft 57. A shaft of the steppingmotor 51 is connected to the shaft 57.

When the projection lens 4 is rotated clockwise about the rotation shaft57 (shaft parallel to the y axis and passing through the optical axis ofthe projection lens 4) as viewed from the +y axis direction, the lightdistribution pattern on the irradiated surface 9 moves to the right (+xaxis direction). Conversely, when the projection lens 4 is rotatedcounterclockwise about the rotation shaft 57 (shaft parallel to the yaxis and passing through the optical axis of the projection lens 4), thelight distribution pattern on the irradiated surface 9 moves to the left(−x axis direction).

With this method, the headlight module 140 can move the lightdistribution pattern on the irradiated surface 9 in the left-rightdirection. In this method, a part to be moved is only the projectionlens 4. The headlight module 140 can smoothly move the lightdistribution pattern in the left-right direction with a small drivingforce. Further, since the angle by which the projection lens 4 isrotated is also small, the light distribution pattern 103 can be movedin a short time.

The headlight module 140 includes the rotation mechanism 50 for rotatingthe projection optical element 4 about the shaft 57 perpendicular to theoptical axis of the projection optical element 4 relative to the lightguide element 3.

In the third embodiment, as an example, the light guide element 3 isdescribed as the light guide component 3. Further, as an example, theprojection optical element 4 is described as the projection lens 4.

The headlight module 140 includes the rotation means 50 for rotating theprojection optical element 4 about the shaft 57 perpendicular to theoptical axis of the projection optical element 4 relative to the lightguide element 3.

As an example, the rotation means 50 is described as the rotationmechanism 50.

Fourth Embodiment

FIG. 22 is a configuration diagram illustrating a configuration of aheadlight module 150 according to a fourth embodiment of the presentinvention. Elements that are the same as in FIG. 1 will be given thesame reference characters, and descriptions thereof will be omitted. Theelements that are the same as in FIG. 1 are the light source 1,condensing lens 2, light guide component 3, and projection lens 4.

As illustrated in FIG. 22, the headlight module 150 according to thefourth embodiment includes the light source 1, the light guide component3, the projection lens 4, a translation mechanism 8, and the controlcircuit 6. The headlight module 150 may include the condensing lens 2.

The translation mechanism 8 moves the projection lens 4 in the y axisdirection. The headlight module 150 differs from the headlight module100 of the first embodiment in having the translation mechanism 8 andcontrol circuit 6.

For example, in a headlight device of an automobile, when people ride ina rear part of the vehicle or when luggage or the like is loaded on therear part of the vehicle, the vehicle body tilts backward. Also when thevehicle accelerates, the vehicle body tilts backward. Further,conversely, when the vehicle decelerates, the vehicle body tiltsforward.

When the vehicle body tilts forward or backward in this manner, theoptical axis of the light distribution pattern of the headlight alsomoves in the up-down direction. That is, when the vehicle body tiltsforward or backward, the light distribution pattern moves in the up-downdirection. Thus, the vehicle cannot obtain an optimum lightdistribution. Here, “vehicle body tilts forward or backward” refers torotation of the vehicle body about an axis of a wheel.

Further, upward movement of the light distribution pattern causes aproblem, such as dazzling an oncoming vehicle.

As a method for reducing the change of the light distribution due to theforward or backward tilt of the vehicle body, a method of tilting theentire headlight device in a direction opposite to the tilt of thevehicle body is commonly used. However, since the conventional techniquetilts the headlight device, it has a problem that a large drivingmechanism is required.

The headlight module 150 according to the fourth embodiment solves sucha problem. The headlight module 150 solves such a problem with a smalland simple structure.

As illustrated in FIG. 22, the translation mechanism 8 includes, forexample, a stepping motor 81, a pinion 82, a rack 83, and a shaft 86.

The translation mechanism 8 of the headlight module 150 according to thefourth embodiment supports the projection lens 4 translatably in the yaxis direction, as illustrated in FIG. 22.

The translation mechanism 8 translates the projection lens 4 in theup-down direction based on a translation amount obtained from thecontrol circuit 6.

A shaft of the stepping motor 81 is connected to the shaft 86. The shaftof the stepping motor 81 and the shaft 86 are disposed in parallel withthe z axis. That is, the shaft of the stepping motor 81 and the shaft 86are disposed in parallel with the optical axis of the projection lens 4.

The pinion 82 is mounted on the shaft 86. An axis of the pinion 82 isparallel to the z axis. Teeth of the pinion 82 mesh with teeth of therack 83. The pinion 82 is disposed on the outer side of the rack 83 withrespect to the projection lens 4.

The rack 83 is mounted on the projection lens 4. The rack 83 is disposedon the right side (+x axis direction side) of the projection lens 4, asviewed in a direction (+z axis direction) from the headlight module 150to the irradiated surface 9. Alternatively, the rack 83 may be disposedon the left side (−x axis direction side) of the projection lens 4, asviewed in a direction (+z axis direction) from the headlight module 150to the irradiated surface 9.

The rack 83 is disposed in parallel with the y axis. That is, the rack83 is disposed so that the teeth of the rack 83 are aligned in thevertical direction (y axis direction).

The teeth of the rack 83 are formed on the outer side with respect tothe projection lens 4. That is, if the rack 83 is disposed on the rightside (+x axis direction side) of the projection lens 4, the teeth of therack 83 are formed on the right side (+x axis direction side) of therack 83. If the rack 83 is disposed on the left side (−x axis directionside) of the projection lens 4, the teeth of the rack 83 are formed onthe left side (−x axis direction side) of the rack 83.

As the stepping motor 81 rotates, the shaft 86 rotates. As the shaft 86rotates, the pinion 82 rotates. That is, the pinion 82 rotates about theaxis of the pinion 82 due to the rotation of the shaft 86. As the pinion82 rotates, the rack 83 moves in the y axis direction. As the rack 83moves in the y axis direction, the projection lens 4 moves in the y axisdirection.

As described above, the translation mechanism 8 translates theprojection lens 4 in the up-down direction based on a translation amountobtained from the control circuit 6.

For example, the control circuit 6 receives a signal of the tilt angleof the vehicle in the forward or backward direction detected by thevehicle body tilt sensor 65. The vehicle body tilt sensor 65 detects thetilt of the vehicle body in the forward or backward direction. Then, thecontrol circuit 6 performs calculation based on the signal of the tiltangle and controls the stepping motor 81. The vehicle body tilt sensor65 is, for example, a sensor, such as a gyro.

For example, it is assumed that the projection lens 4 is a lens thatimages the emitting surface 32 at a magnification of 1000 onto theirradiated surface 9 located 25 m ahead. If it is assumed that thevehicle body tilts upward by 5 degrees in the front-back direction,displacement of the optical axis at 25 m ahead is represented by thefollowing formula (4). “Vehicle body is upward in the front-backdirection” refers to a state where the front side of the vehicle body isabove the rear side. “·” used in the formulae (1) and (2) is equivalentto “×” used in the formula (4) and denotes “multiplication.”

25000 [mm]×tan 5 [deg]=2187.2 [mm]  (4).

That is, the optical axis is displaced from a predetermined position by2187.2 mm upward (in the +y axis direction). “Predetermined” here refersto a position of the optical axis when the vehicle body is not tilted.Since the magnification is 1000, the amount of shift of the projectionlens 4 required to correct the displacement of the optical axis isrepresented by the following formula (5):

2187.2 [mm]/1000=2.19 [mm]  (5).

Only by moving (translating) the projection lens 4 by 2.19 mm downward,the displacement of the optical axis can be corrected. Further,conversely, if the vehicle body tilts downward by 5 degrees in thefront-back direction, the projection lens 4 should be translated by 2.19mm upward, contrary to the above description. “Vehicle body is downwardin the front-back direction” refers to a state in which the rear side ofthe vehicle body is above the front side.

In this manner, the headlight module 150 according to the fourthembodiment can correct the displacement of the optical axis in theup-down direction (y axis direction) due to tilt of the vehicle body inthe front-back direction, by slightly translating the projection lens 4in the y axis direction. “Tilt of the vehicle body in the front-backdirection” indicates that the rear side of the vehicle body and thefront side of the vehicle body are different in height.

This eliminates the need for drive of the entire headlight device, whichhas been common up to now. Thus, the load on the driving part isreduced. Further, since the diameter of the projection lens 4 is small,a small and simple optical axis adjuster can be achieved. Further, sincethe distance by which the projection lens 4 is translated is also small,the light distribution pattern 103 can be moved in a short time.

In the headlight module 150 of the fourth embodiment, the projectionlens 4 is translated in the up-down direction (y axis direction)relative to the light guide component 3. However, as a method fortranslating the light distribution pattern in the up-down direction withrespect to the traveling direction of the vehicle as in the fourthembodiment, the following method may be used.

For example, the same advantages can be obtained by a method of turningthe projection lens 4 in the up-down direction, i.e., a method ofrotating the projection lens 4 about an axis parallel to the x axis andpassing through the optical axis of the projection lens 4.

When the projection lens 4 is rotated clockwise about a rotational axis(axis parallel to the x axis and passing through the optical axis) asviewed from the +x axis direction, the light distribution pattern on theirradiated surface 9 moves downward (−y axis direction). Conversely,when the projection lens 4 is rotated counterclockwise about therotational axis (axis parallel to the x axis and passing through theoptical axis), the light distribution pattern on the irradiated surface9 moves upward (+y axis direction).

With this method, it is possible to easily move the light distributionpattern on the irradiated surface 9 in the up-down direction. Also inthis method, a part to be moved is only the projection lens 4, and theoptical axis can be smoothly adjusted with a small driving force.Further, since the angle by which the projection lens 4 is rotated isalso small, the light distribution pattern 103 can be moved in a shorttime.

The headlight module 150 according to the fourth embodiment translatesthe projection lens 4 of the headlight module 100 according to the firstembodiment in the up-down direction (y axis direction) of the vehicle.Alternatively, the headlight module 150 turns the projection lens 4 ofthe headlight module 100 according to the first embodiment in theup-down direction (y axis direction) of the vehicle.

The configuration described in the fourth embodiment is also applicableto the headlight module 110.

Further, the same advantages can also be obtained by translating, in theup-down direction (y axis direction) of the vehicle, the projection lens4 of any of the headlight module 120 according to the second embodimentand the headlight module 130 according to the third embodiment. The sameadvantages can also be obtained by turning, in the up-down direction (yaxis direction) of the vehicle, the projection lens 4 of any of theheadlight module 120 according to the second embodiment and theheadlight module 130 according to the third embodiment. In these cases,the rotation mechanism 5 of the headlight module 120 or the translationmechanism 7 of the headlight module 130 needs to be moved or rotatedtogether with the projection lens 4.

Further, as described later, in a headlight device 250 includingmultiple headlight modules, the headlight modules may be assigned todifferent illumination areas. In such a case, the directions of movementof the illumination areas of the headlight modules are not necessarilylimited to the left-right direction (third embodiment) or the up-downdirection (fourth embodiment).

For example, a headlight module assigned to a high illuminance region inthe light distribution pattern may move the illumination area in anoblique direction or the like in accordance with the driving situationof the vehicle.

In such a case, by rotating the configuration described in the thirdembodiment or fourth embodiment about an optical axis to arrange it, itis possible to move the illumination area to an arbitrary position on aplane (irradiated surface 9) perpendicular to the optical axis.

That is, the projection lens 4 moves on a plane perpendicular to theoptical axis of the projection lens 4, thereby changing the emissiondirection of the emitted light. Alternatively, the projection lens 4rotates about an axis perpendicular to the optical axis of theprojection lens 4, thereby changing the emission direction of theemitted light.

The headlight module 150 includes the translation mechanism 8 fortranslating the projection optical element 4 in a directionperpendicular to the optical axis of the projection optical element 4relative to the light guide element 3.

In the fourth embodiment, as an example, the light guide element 3 isdescribed as the light guide component 3. Further, as an example, theprojection optical element 4 is described as the projection lens 4.

The headlight module 150 includes the translation means 8 fortranslating the projection optical element 4 in a directionperpendicular to the optical axis of the projection optical element 4relative to the light guide element 3.

As an example, the translation means 8 is described as the translationmechanism 8.

Fifth Embodiment

FIG. 23 is a configuration diagram illustrating a configuration of theheadlight device 250 having the headlight module 100, 110, 120, 130,140, or 150. In the above embodiments, the embodiments of the headlightmodules 100, 110, 120, 130, 140, and 150 are described. In FIG. 23, asan example, an example having the headlight modules 100 is illustrated.

For example, all or a subset of the three headlight modules 100illustrated in FIG. 23 may be replaced with the headlight modules 110,120, 130, 140, or 150.

The headlight device 250 includes a housing 97. Further, the headlightdevice 250 may include a cover 96.

The housing 97 holds the headlight modules 100.

The housing 97 is disposed inside a vehicle body.

The headlight modules 100 are housed inside the housing 97. In FIG. 23,as an example, the three headlight modules 100 are housed. The number ofheadlight modules 100 is not limited to three. The number of headlightmodules 100 may be one or three or more.

The headlight modules 100 are arranged in the x axis direction insidethe housing 97, for example. Arrangement of the headlight modules 100 isnot limited to the arrangement in the x axis direction. In view of thedesign, function, or the like, the headlight modules 100 may bedisplaced from each other in the y or z axis direction.

Further, in FIG. 23, the headlight modules 100 are housed inside thehousing 97.

However, the housing 97 need not have a box shape. The housing 97 mayconsist of a frame or the like and have a configuration in which theheadlight modules 100 are fixed to the frame. This is because in thecase of a four-wheeled automobile or the like, the housing 97 isdisposed inside the vehicle body. The frame or the like may be a partconstituting the vehicle body. In this case, the housing 97 is a housingpart that is a part constituting the vehicle body.

In the case of a motorcycle, the housing 97 is disposed near the handle.In the case of a four-wheeled automobile, the housing 97 is disposedinside the vehicle body.

The cover 96 transmits light emitted from the headlight modules 100. Thelight passing through the cover 96 is emitted in front of the vehicle.The cover 96 is made of transparent material.

The cover 96 is disposed at a surface part of the vehicle body andexposed on the outside of the vehicle body.

The cover 96 is disposed in the z axis direction from the housing 97.

Light emitted from a headlight module 100 passes through the cover 96and is emitted in front of the vehicle. In FIG. 23, the light emittedfrom the cover 96 is superposed with light emitted from the adjacentheadlight modules 100 to form a single light distribution pattern.

The cover 96 is provided to protect the headlight modules 100 fromweather, dust, or the like. However, if the projection lens 4 isconfigured to protect the components inside the headlight modules 100from weather, dust, or the like, there is no need to provide the cover96.

As described above, if the headlight device 250 has multiple headlightmodules 100, it is an assembly of the headlight modules 100. Further, ifthe headlight device 250 has a single headlight module 100, it is equalto the headlight module 100. That is, the headlight module 100 is theheadlight device 250.

The above-described embodiments use terms, such as “parallel” or“perpendicular”, indicating the positional relationships between partsor the shapes of parts. These terms are intended to include rangestaking account of manufacturing tolerances, assembly variations, or thelike. Thus, recitations in the claims indicating the positionalrelationships between parts or the shapes of parts are intended toinclude ranges taking account of manufacturing tolerances, assemblyvariations, or the like.

Further, although the embodiments of the present invention are describedas above, the present invention is not limited to these embodiments.

DESCRIPTION OF REFERENCE CHARACTERS

100, 110, 120, 130, 140, 150 headlight module, 250 headlight device, 1light source, 11 light emitting surface, 15 a, 15 b, 15 c light sourcemodule, 2 condensing lens, 211, 212 incident surface, 22 reflectingsurface, 231, 232 emitting surface, 232 a, 232 b region, 3, 30, 35 lightguide component, 31 incident surface, 32 emitting surface, 321 edge, 33reflecting surface, 4 projection lens, 5, 50 rotation mechanism, 51stepping motor, 52, 53, 54, 55 gear, 56, 57 shaft, 6 control circuit, 65vehicle body tilt sensor, 66 vehicle body state sensor, 7 translationmechanism, 71 stepping motor, 72 pinion, 73 rack, 76 shaft, 8translation mechanism, 81 stepping motor, 82 pinion, 83 rack, 86 shaft,9 irradiated surface, 91 cutoff line, 92 region on the lower side of thecutoff line, 93 brightest region, 94 motorcycle, 95 wheel, 96 cover, 97housing, 98 position in contact with the ground, 101 line indicating aroad surface, 102 center line, 103, 104, 106 light distribution pattern,105 corner area, PH light concentration position, S_(out), S_(out1),S_(out2) emission angle, S₁, S₃, S₄, S₆ incident angle, S₂, S₅reflection angle, m₁, m₂, m₃, m₄ perpendicular line, d tilt angle, Qpoint.

1. A headlight module comprising: a light source for emitting light; acondensing element for concentrating light emitted from the lightsource; a light guide element having an incident surface for receivinglight emitted from the condensing element, a reflecting surface forreflecting the received light, and an emitting surface for emitting thereceived light; and a projection optical element for projecting a firstlight distribution pattern formed on the emitting surface, as a secondlight distribution pattern, wherein the incident surface has positiverefractive power or negative refractive power, wherein a condensingfunction of the condensing element and the incident surface forms ashape of the first light distribution pattern, wherein the reflectingsurface superposes light that enters through the incident surface and isreflected at the reflecting surface and light that enters through theincident surface and is not reflected at the reflecting surface on theemitting surface, thereby forming a high luminous intensity region onthe emitting surface, and wherein the high luminous intensity region isformed in a region of the first light distribution pattern.
 2. Theheadlight module of claim 1, wherein the emitting surface has a curvedsurface shape.
 3. The headlight module of claim 1, wherein in a lightbeam entering the light guide element from the condensing element, in anormal direction of the reflecting surface, a light concentrationposition of a first light ray at an end on a front surface side of thereflecting surface is farther from the condensing element than a lightconcentration position of a second light ray at an end on a sideopposite to the first light ray.
 4. A headlight module comprising: alight source for emitting light; a light guide element having anincident surface for receiving light emitted from the light source, areflecting surface for reflecting the received light, and an emittingsurface for emitting the received light; and a projection opticalelement for projecting a first light distribution pattern formed on theemitting surface, as a second light distribution pattern, wherein theincident surface has positive refractive power, wherein the incidentsurface forms a shape of the first light distribution pattern bychanging a divergence angle of light entering through the incidentsurface, wherein the reflecting surface superposes light that entersthrough the incident surface and is reflected at the reflecting surfaceand light that enters through the incident surface and is not reflectedat the reflecting surface on the emitting surface, thereby forming ahigh luminous intensity region on the emitting surface, and wherein thehigh luminous intensity region is formed in a region of the first lightdistribution pattern.
 5. The headlight module of claim 4, wherein theemitting surface has a curved surface shape.
 6. The headlight module ofclaim 4, wherein when viewed in a first plane that is a plane parallelto a direction in which the light guide element emits light andperpendicular to the reflecting surface, the incident surface haspositive refractive power.
 7. The headlight module of claim 6, whereinthe incident surface has a first focal point in the first plane, andwherein when viewed in a second plane that is a plane parallel to thedirection in which the light guide element emits light and perpendicularto the first plane, the incident surface has positive refractive powerso as to have a second focal point at a position different from thefirst focal point in the direction in which the light guide elementemits light.
 8. The headlight module of claim 6, wherein when viewed ina second plane that is a plane parallel to the direction in which thelight guide element emits light and perpendicular to the first plane,the incident surface has negative refractive power.
 9. The headlightmodule of claim 4, further comprising a condensing element forconcentrating light emitted from the light source, wherein in a lightbeam entering the light guide element from the condensing element, in anormal direction of the reflecting surface, a light concentrationposition of a first light ray at an end on a front surface side of thereflecting surface is farther from the condensing element than a lightconcentration position of a second light ray at an end on a sideopposite to the first light ray.
 10. The headlight module of claim 1,wherein an end portion of the reflecting surface in a direction in whichthe received light travels in the light guide element includes a pointlocated at a position of a focal point of the projection optical elementin a direction of an optical axis of the projection optical element. 11.The headlight module of claim 4, wherein an end portion of thereflecting surface in a direction in which the received light travels inthe light guide element includes a point located at a position of afocal point of the projection optical element in a direction of anoptical axis of the projection optical element.
 12. The headlight moduleof claim 1, wherein the light source is a solid-state light sourcehaving directivity.
 13. The headlight module of claim 4, wherein thelight source is a solid-state light source having directivity.
 14. Theheadlight module of claim 12, wherein the projection optical elementprojects a shape of a light emitting surface of the light source. 15.The headlight module of claim 13, wherein the projection optical elementprojects a shape of a light emitting surface of the light source. 16.The headlight module of claim 1, wherein the reflecting surface isinclined so that an optical path in the light guide element becomeswider in a direction in which the received light travels in the lightguide element.
 17. The headlight module of claim 4, wherein thereflecting surface is inclined so that an optical path in the lightguide element becomes wider in a direction in which the received lighttravels in the light guide element.
 18. A headlight device comprisingthe headlight module of claim
 1. 19. A headlight device comprising theheadlight module of claim 4.